Where did immigrants come at different periods of US history? What were the major push and pull factors for the different waves of immigrants? How...

There have been three major waves of immigration to the United States if we look from the beginning of the country to the present day.  The first wave came in the 1840s.  The next wave came beginning around 1890 and ending with WWI.  The final wave of immigration is the one in which we are currently living.  It has been going on for roughly the last 30 years.

The first wave of immigration featured people from Ireland and Germany.  The push factors were economic in the case of the Irish and mostly political in the case of the Germans.  It was during this decade that a terrible potato famine devastated Ireland’s farms.  Huge numbers of Irish fled the country in order to avoid starvation.  In the late 1840s, Germany was hit by political upheaval.  A democratic revolution occurred but failed.  This pushed out many Germans who feared that the government would retaliate against them for having participated in the revolution.

The second wave of immigration mainly consisted of people from Southern and Eastern Europe.  These were Italians, Greeks, Poles, and others.  The push factors for these people were both economic and political/religious.  The Southern Europeans generally came for economic reasons as they lived in very poor countries.  Many of the Eastern Europeans were forced out of their countries largely because they were being persecuted for being Jewish.

The final wave of immigration has come from Asia and Latin America.  This wave has been motivated almost completely by economic factors.  However, some of the immigrants have been pushed out by political factors.  Examples of this would include some of the immigrants from China and many of the immigrants from Vietnam, particularly in the time after the Vietnam War.

In all cases, there have been two major pull factors.  First, the United States has been seen as the land of opportunity.  People have believed that they would be able to find jobs in the US.  Second, the US has been seen as the “land of the free,” a place where immigrants of all sorts could fit in and become part of the country, regardless of ethnicity or religion.  These factors have attracted people to the US at all points in our history.

All waves of immigrants have been treated with a mixture of welcome and hostility.  Some Americans have welcomed them because of their potential to help our economy.  Others have opposed immigration on the grounds that immigrants were unwilling to assimilate, that they brought health risks, that they were likely to commit crimes, that they were politically undesirable, and that they were the wrong religion.  Such attitudes have sprung up among such groups as the Know-Nothings in the 1850s and the KKK in the 1920s, and in support for anti-immigrant politicians today.

What managerial skills are displayed by a leader?

According to Brian Tracey, leaders must display management skills. The following managerial skills are referenced in Brian’s article entitled What Makes a Good Leader? Simple Ways to Improve Your Management Skills.

Listening to others is a top managerial skill displayed by leaders. Brian explains that the best way to measure the success of a leader is to encourage feedback from the people the leader manages. By be listened to by others, people feel acknowledged and visible. In fact, managers who “encourage a dialogue with the team (come) out on top”.

Careerfaqs also identifies top management skills employed by leaders. These skills include: selecting the right employees for a job, showing empathy, open and clear communication, proper and fair delegation of work, thanking and rewarding staff, the development of staff through proper coaching, encouragement, and flexibility.

What does Nick mean when and why does he say this: "Angry as I was, as we all were, I was tempted to laugh whenever he opened his mouth. The...

Nick is basically noting (to himself) what a hypocrite Tom is. Tom is giving Gatsby a hard time because he knows that something is going on between Gatsby and Daisy, Tom's wife. Nick finds this amusing and hypocritical because Tom has been cheating on Daisy for a much longer time. This is why Nick says he is tempted to laugh every time Tom opens his mouth. Who knows what hypocritical thing Tom might say next?

Nick notes that Tom illustrates a transition from libertine to prig. A libertine, in this context, is one who ignores social morality and responsibility, namely in sexual matters. Tom is a libertine in the sense that he cheats on his wife. Tom then becomes judgmental of Gatsby and Daisy, reprimanding them for having an affair. So, Tom is a libertine in his personal life, but he takes this stance as a prig, a self-righteous person who thinks he has the right to judge others. From a cheating husband to one who faults his wife for cheating, the "transition from libertine to prig was so complete." What makes Tom's self-righteous behavior even more hypocritical is the racist commentary Tom is also keen on making. 

Describe Miss Maudie Atkinson. Why does Scout like her so much?

Miss Maudie Atkinson is the Finch's magnanimous neighbor who is also a morally upright individual like Atticus. Scout describes her as a "chameleon lady" with an "acid tongue" who enjoys everything about the outdoors. Maudie is a lovely lady who keeps Scout company when she feels neglected by Jem and Dill. Maudie generously allows the children to play in her yard, just as long as they don't ruin her azaleas or jump on the arbor. She even treats the children to tasty cakes several times throughout the novel. Maudie is always there for her and gives Scout and Jem words of encouragement following the devastating Tom Robinson trial. In Chapter 24, Maudie's presence comforts Scout when she participates in the missionary circle. Scout gets nervous when the ladies begin to ask her questions, and Maudie softly touches Scout's hand which calms her down and makes Scout feel secure. Maudie's benevolent attitude and willingness to share her time with Scout is the reason Scout enjoys her company and considers Maudie a friend.

Calculate the percent composition and determine the molecular formula and the empirical formula for the nitrogen-oxygen compound that results when...

We can write the reaction for this problem as:

`~N_2` + `~O_2` -> `~N_xO_y`

x = subscript for N in the product

y = subscript for O in the product

Determine the grams of `~O_2 ` :

We are given the grams of `~N_2` and `~N_xO_y` :

    `~N_2` = 12.04 g

    `~N_xO_y` = 39.54 g

We can use the Law of Conservation of Mass to determine the grams of `~O_2` .

According to the Law of Conservation of Mass, the mass of the reactants in a chemical reaction is equal to the mass of the products.

    mass `~N_2` + mass `~O_2` = mass `~N_xO_y`

        12.04 g + ? g `~O_2` = 39.54 g

           ` ~O_2` = 39.54 g – 12.04 g

                   = 27.5 g``

Determine the empirical formula:

Step 1: Convert grams of nitrogen and oxygen to moles.

Convert grams to moles by dividing by the molar mass of each element.

   N: 12.04 g x (1 mol/14.007 g) = 0.860 mol

   O: 27.5 g x (1 mol/15.999 g) = 1.72 mol

Step 2: Divide both answers from Step 1 by the smallest answer from Step 1.

   N: 0.860/0.860 = 1

   O: 1.72/0.860 = 2

Step 3: Use the answers to Step 2 as subscripts for the empirical formula.

   The empirical formula is `~NO_2` ` `

Determine the molecular formula:

We are given the molar mass of the product `~N_xO_y` as 92.02 g

Step 1: Determine the molar mass of the empirical formula `~NO_2` .

molar mass of `~NO_2 ` = 14.007 + (2)(15.999) = 46.005 g

Step 2: Divide the given molar mass of the product by the molar mass of the empirical formula.

  92.02/46.005 = 2

Step 3: Multiply the subscripts of the empirical formula by the answer to Step 2.

   2 x `~N_1O_2` = `~N_2O_4`

The molecular formula is `~N_2O_4` .

Determine the percent composition of the product `~N_2O_4` .

Step 1: Determine the molar mass of each element in the product.

   N: (2)(14.007) = 28.014 g

   O: (4)(15.999) = 63.996 g

Step 2: Determine the molar mass for the entire product.

   `~N_2O_4` : 28.014 + 63.996 = 92.01 g

Step 3: Divide the molar mass of each element by the molar mass of the entire product and multiply by 100.

   % N: (28.014/92.01) x 100 = 30.4%

   % O: (63.996/92.01) x 100 = 69.6%

A 300-gallon hot tub is supplied with solar heated water, 10 degrees above tub temp. If the solar water flows at 1 gal per minute, how long will it...

When bodies at two different temperatures interact, one of them loses heat, while the other gains some heat. In this process, the body with the higher temperature comes down to a lower temperature, while the one with the lower temperature will gain heat and hence be at a higher temperature. 

When water 10 degrees hotter is added to the tub, the water that is already in the tub (if any) will gain heat and the supplied water will lose heat. However, to gain 10 degrees, all the water originally present in the tub will have to be replaced by the hot water from the solar heater. 

Thus, 300 gallons of hot water is needed. Since the rate of hot water flow is 1 gallon per minute, it will take 300 min for the temperature of the tub's water to rise by 10 degrees F.

Hope this helps. 

In the language of grief in Act 4 of Shakespeare's Romeo and Juliet, what does the first quotation reveal about Capulet's attitude toward Juliet?

When the Nurse first tells Lord Capulet that Juliet has died, he doesn't believe it.  He insists on seeing her himself.  When he does, he confirms that she has been dead for some hours because her body is now cold and her joints are stiff.  He says, "Death lies on her like an untimely frost / Upon the sweetest flower of all the field" (4.5.33-34).  Here, he uses a metaphor to compare Juliet to the prettiest flower in existence, and death is the frost that comes too early and kills that flower.  Therefore, despite his earlier threats to throw her out and let her starve in the streets if she disobeys him and refuses to marry Count Paris, it does seem that Lord Capulet cares for daughter.  It is telling, however, that his first comment upon her death addresses her beauty (rather than some other, more important, quality); it could indicate that he sees her as more of a possession than a person, an interpretation supported by his claim, "An you be mine, I'll give you to my friend" (3.5.203). 

In the "The Revolt of Mother" by Mary Wilkins Freeman, why does Adoniram refuse to explain his decision to build a new barn to his wife?

Since the story is written from the limited point of view of Sarah Penn, readers don't have the ability to get inside Adoniram Penn's head to understand his motivations. However, from his actions and words, and from Sarah's words, readers can infer his motivations. The story begins with Sarah asking Adoniram why men are digging in the field, and Adoniram unwillingly divulges that they are building a barn, but not until expressing to Sarah that she should "'tend to your own affairs." He implies that running the farm, including making decisions about outbuildings, is his domain, not Sarah's. Throughout the play signs of the patriarchal rule in the Penn family are apparent, most specifically when Sarah Penn explains to her daughter that she will one day find out that "we know only what men-folks think we do ... an' how we ought to reckon men-folks in with Providence, an' not complain of what they do any more than we do of the weather." 

As much as Adoniram believes he has the authority and right to build the barn, he nevertheless certainly experiences twinges of conscience about his decision, which also probably motivates him to keep his wife in the dark about the barn. (His tears at the end of the story may indicate a heart soft enough to feel guilt.) He knows without Sarah's reminders that he promised her 40 years previously to build her a new house on the very place where he is now erecting his new barn. Yet when she confronts him on his failure to keep his promise, he replies, "I ain't got nothin' to say." One reason for his silence is that he cannot refute her allegations or her logic. Another is that he may feel guilty about his choices. But in the end, he employs silence as a defense against Sarah's influence so that he can continue to have his own way: "Her opponent employed that obstinate silence which makes eloquence futile with mocking echoes." 

From the clues in the story, readers can deduce that Adoniram refuses to explain his decision about the barn to Sarah because his reasons are indefensible given his prior promises, because he may feel somewhat guilty for having broken faith with his wife on the issue, because he wants his own way, and because the patriarchal system their marriage functions under allows him to do so. 

How did Hitler take over land in the 1930s?

Hitler began German expansion by annexing neighboring Austria in 1938. This act, known as the Anschluss, was conducted with what was claimed to be overwhelming Austrian support. Hitler claimed that Germans within Austria, a predominately German-speaking state, were begging to be joined with Germany to create a larger Germany. He strong-armed the Austrian chancellor into accepting Nazi politicians in his government, and then eventually occupied Austria, formally incorporating his homeland into Germany. He then turned to the Sudetenland, a region in neighboring Czechoslovakia with a large German presence. He again fabricated a crisis, claiming that Sudeten Germans faced persecution, and demanding that the Czechoslovak government cede Germany the territory or face war. At the Munich Conference of 1938, the powers of Europe, most prominently British Prime Minister Neville Chamberlain, pursued a policy of appeasement, granting Hitler the territory in return for a promise that he would not invade Czechoslovakia. He invaded that country within a few months, and invaded Poland (after concluding a non-aggression pact with the Soviet Union) in September of 1939. While the Poles, unlike the Austrians or Czechoslovakia, staged military resistance, they were quickly overrun by the devastating combination of air power and mechanized forces. This new form of warfare, known as blitzkrieg, would be visited on much of Western Europe in 1940. 

Are there allusions to other texts or allegorical characters in The Picture of Dorian Gray?

In The Picture of Dorian Gray, Wilde refers to a number of other texts and allegorical characters as he develops the novel's key themes and characters. In fact, this process starts as early as Chapter One when Wilde (through Lord Henry) likens Dorian Gray to Adonis, a figure in Greek mythology. This likeness is important in the characterization of Dorian because it demonstrates his extreme beauty and also foreshadows the conflict between Basil and Lord Henry as they vie for Dorian's attentions (just like Aphrodite and Persephone in the Greek myth). Similarly, a further Greek reference to Narcissus, again made by Lord Henry, foreshadows the corruption of Dorian's soul as he comes to recognize his own beauty.

In addition, with the Yellow Book, academics believe that Wilde makes a reference to a contemporary text called A Rebours (Against Nature) which was written by Joris-Karl Huysmans in 1884. A Rebours tells the story of a man who rejects society and creates his own world filled with personal pleasures and desires. Like A Rebours, the Yellow Book inspires Dorian's hedonistic and self-indulgent lifestyle. In turn, this propels Dorian to the depths of moral corruption while simultaneously causing his portrait to physically degrade.

(You can find more information about A Rebours and its influence on Oscar Wilde in the second reference link provided.)

What is a good thesis for The Giver by Lois Lowry?

There are many good thesis possibilities for The Giver. The book has so much to teach us about how not to live.  Let's look at a few possibilities.

One potential thesis from The Giver is that not having choices is a form of slavery.  The people in the story have few choices in life. What their careers are going to be is decided for them. Whom they will partner with to raise children with is not within their control. They are "given" children and have no choice about this.  Even who will bear the children is decided by the Elders.  This is, in effect, a community of slaves. 

Another possibility is the thesis that people are not fully human if they are prevented from experiencing emotions.  The people in The Giver have had all of their emotions repressed. They do not experience hatred, jealousy, or envy.  That doesn't sound too terrible.  On the other hand, though, they do not experience sexual longings. Nor do they experience love.  There can be no true happiness without unhappiness, and the story supports this thesis very well.

Still another thesis is that sameness is a dreadful idea, taking away the wonderful variability of life.  This is true in ways large and small.  There are no hills and valleys in The Giver. There is no stormy weather.  People's clothing, housing, and furnishings are all the same.  There is no color.  There is a schedule from which there are few deviations. This kind of sameness would be terrible for anyone to live with, since while we do feel best with some routine, we also need some variability. 

Each of these theses can be fully supported from the text, and when you write your thesis statement, remember that it must include your thesis and your supporting points, too. For example, here is a thesis statement I might write for The Giver:

The Giver shows that depriving people of memory is a way of dehumanizing and endangering them. 

That gives me two points to make in my essay, one on dehumanizing people and other on endangering them.  I can support my idea now with examples of each from the story.  For your thesis statement, you can do the same, with your thesis, your main idea, and your supporting points. 

What political issue did the three-fifth's compromise in the Constitution attempt to address?

The southern colonies feared that in any new government designed as a representative democracy, they would lose power because the populations of their states were comprised in large part of slaves, who could not vote. Northern states, by contrast, had very few slaves, and their populations were mostly free, meaning that if representation in congress was proportional and based solely on the number of free men in each state, then the voting power of the southern states would be massively diluted. The southern states did not want to lose their political influence, and refused to sign onto a constitution that would relegate them to being lesser powers with many fewer representatives in the federal legislature.

So the southern states proposed that for purposes of allocating representatives to the House of Representatives, slaves living in their states should be counted. Yet delegates to the Constitutional Convention from the northern states rejected this plan, because it would give the slaveowners in those southern states vastly more representation than any free men in the north, and would tilt the balance of power in the Congress toward southern states and their economic agenda, which were at odds with the agendas of the northern states.

In order to satisfy the southern states that their interests would be represented in the new government, and in order to quell the fears of less populous northern farming states, like New Jersey, delegates to the Constitutional Convention came up with the 3/5th's rule. This rule stated that although slaves would not get the right to vote, be citizens, or have another individual rights, for purposes of allocating representatives in the government, each slaves would be counted as 3/5th of a person. This would give the southern states more representatives than if slaves were not counted at all, but not so many representatives as if each slave were counted as a full person. 

The irony of this decision is that this rule benefitted white plantation owners with thousands of slaves at the expense of both slaves and poor white farmers. The voting power that accrued to states like Virginia and South Carolina as a result of the 3/5th's law was incredibly anti-democratic, and went to perpetuating the institution of slavery. Had the 3/5th's law not been established, slavery might have been abolished much sooner, through votes in a less deadlocked congress, and the country might have avoided the Civil War.

How can I formulate a thesis statement and three topic questions for a critical analysis of leadership roles in Lord of the Flies?

The characters in Lord of the Flies illustrate that a good leader puts the needs of the group ahead of his personal desires and respects his followers. One could develop this thesis by asking: 1. What negative qualities of good leadership does Jack display? 2. Why is Piggy not a good leader despite his intelligence? 3. What makes Ralph a good leader? 

To discuss the things that make Jack a poor leader, you can refer to his constant desire for acclaim, the way he puts his own desires above the needs of the group, and his disrespect for his followers. He gets angry when he's not in charge--which causes him to storm away after the boys fail to vote against Ralph in chapter 8. He lets the signal fire go out in order to kill the pig. At one point, in chapter 6, he tries to stifle the free speech rights of the other boys. And, of course, he uses theft and violence against the others.

Piggy is highly intelligent, which you can prove from the beginning in chapter 1 and from Ralph's statement in chapter 5 that "Piggy could think....Piggy...had brains." But Piggy lacks respect for the other boys. Although they mock him because of how different he is, he shows plenty of disdain for them, too. You can find many quotes to show how he speaks judgmentally to the others and acts superior to them.

Finally, in showing Ralph as the example of good leadership, give examples of how he puts others' needs before his own and how he respects others. In chapter 1, but he is willing to put off having fun in order to build the shelters. He also takes his role as chief seriously, coming up with rules for division of labor, fire safety, and sanitation. He keeps the signal fire in mind all the time. When someone has to be the one to go see "the beast," he volunteers to go first, despite his fear. He respects the other boys--he lets Jack take charge of the choir boys and hunting. He is willing to listen to the other boys during meetings. He also stands up for Piggy against Jack. 

Taken together, the examples of these three boys show that a good leader respects his followers and subjugates his own desires for the good of the group.

How can I identify the key challenges presented in the macro-environment of an organization (in this case Karlis Tyres, a B2C company, selling...

It is important to consider three factors in the given task when taking into consideration macro-economic factors: 

- The company operates in Greece

- It is a B2C company

- It sells tires and shock absorbers

Based on these factors, here are some key challenges that the company may face when implementing its Digital Marketing strategy.

1.) As Greece is an extremely unstable economic state (Eurozone crisis, Grexit, high unemployment), the company, and in fact ANY company, may face difficulties selling their goods to consumers in Greece. 

--> Macro-economic factor: unstable economy

2.) Since the company sells to consumers directly, it may face difficulties converting sales from its Digital Marketing strategy with a product that is traditionally sold at a B2B level (tire companies sell to garages, repair shops, and retail outlets).

--> Macro-economic factor: competitive B2B market

3.) Finally and most importantly, it is important to understand that the company sells goods that are traditionally bought at physical retail outlets. While the company may raise awareness through its Digital Marketing strategy, it may be very difficult to sell tires and shock absorbers online as consumers usually want to physically see and touch these type of products to ensure their quality. 

--> Macro-economic factor: consumer trend/opinion

I hope that this helps!

What To Kill a Mockingbird quotes show Boo Radley is a caring person?

Boo Radley watches out for the Finch children and even saves their lives.

Boo Radley is a sensitive and reclusive man. His nickname comes from the fact that he never leaves his house. Many neighborhood legends describe him as a monster. This is mostly based on Boo's misspent childhood, where he acted out against his religiously fanatical family.

The first time Boo reaches out to the children to try to make friends, he leaves them gifts in a tree on his property that they pass on the way home from school. The gifts are small things children would appreciate, such as gum, twine, a pocket watch, pennies, and a spelling bee medal. The soap dolls are so accurate that they frighten Scout.

They were almost perfect miniatures of two children. The boy had on shorts, and a shock of soapy hair fell to his eyebrows. I looked up at Jem. A point of straight brown hair kicked downwards from his part. I had never noticed it before. Jem looked from the girl-doll to me. The girl-doll wore bangs. So did I (Chapter 7).

In addition to these gifts, Boo rescues Jem’s pants when he left them behind when escaping the Radley porch. Boo inexpertly sews them up and leaves them for Jem to find so he would not get in trouble. 

They’d been sewed up. Not like a lady sewed ‘em, like somethin’ I’d try to do. All crooked. It’s almost like—”

“—somebody knew you were comin‘ back for ’em” (Chapter 7).

Jem is baffled by this, but it is an example of how considerate and protective Boo is toward the Finch children. 

When Miss Maudie’s house catches fire, Boo sneaks out and puts a blanket on Scout's shoulders. She does not even realize this until Atticus asks her where it came from. Jem knows it was Boo Radley that put it there and begs Atticus not to tell. He does not want to make trouble for Boo. 

“That’s all right, son.” Atticus grinned slowly. “Looks like all of Maycomb was out tonight, in one way or another” (Chapter 8).

Boo’s biggest protective gesture is to save the children from Bob Ewell. He must have been watching Scout and Jem return from the pageant Halloween night. Bob Ewell attacks them, but Boo Radley is there. He protects them and kills Ewell. Because of Boo, Jem only breaks his arm and Scout isn’t badly hurt because she had a thick ham costume on. 

Boo almost never talks when he is at the Finch house.  Atticus and Heck Tate agree to keep what happened secret, telling everyone Bob Ewell was drunk and fell on his knife. Scout walks Boo home, but Atticus makes sure to thank him for saving his children.  

Atticus put his face in my hair and rubbed it. When he got up and walked across the porch into the shadows, his youthful step had returned. Before he went inside the house, he stopped in front of Boo Radley. “Thank you for my children, Arthur,” he said (Chapter 30).

Boo Radley is hardly the monster the children think he is at the beginning of the book. He is a good friend who looks out for Scout and Jem and eventually saves their lives. Scout stands on his porch and feels like she understands what his life is like. He is lonely and shy, and this was the only way he could make friends.

How does Dickens present Scrooge's character in Stave Five of A Christmas Carol?

Charles Dickens presents Scrooge as a completely transformed man in the final stave of A Christmas Carol.  At the beginning of the book, Scrooge growls in his miserliness.  At the end of the book, Scrooge chuckles in his mirth.  This is exemplified in the following exclamation:

I am as light as a feather, I am as happy as an angel, I am as merry as a schoolboy. I am as giddy as a drunken man. A merry Christmas to everybody! A happy New Year to all the world.

Dickens goes even further than this, though.  Scrooge not only talks about how he has changed, Scrooge acts upon it as well.  The largest generous gestures involve Bob Cratchit and his family.  Specifically, Scrooge sends them the prize Christmas goose in order to cook for their dinner and begin another transformation:  that of Tiny Tim.  Next, Scrooge raises Cratchit’s salary in order to lift the Cratchit family out of the depths of poverty. 

As a final thought, Dickens adds that we should become like Scrooge here because “he knew how to keep Christmas well.”  Dickens indicates this by this sentence:  “May that be truly said of us, and all of us!”  The difference in Scrooge’s character is astounding.  In short, this final part of the book serves as a final contrast to the beginning.  It is now the reader’s best interest to behave like Scrooge in every way.

How might one deal with empathy in the classroom?

Empathy is a very important tool that teachers can utilize in the classroom. When I was completing my undergraduate work, the professor of my multi-cultural education class made a profound statement that stuck with me. He said "students don't care how much you know until they know how much you care." I realize that he did not come up with that phrase, but it was the first time that I heard it and it stuck with me.  As I read your question, this statement came to my mind again. How can students know how much you care if you are not practicing empathy in the classroom? Recent science also seems to confirm the importance of teachers practicing empathy. Consider the following remark from Vicki Zakrewski, the education director at Greater Good Science Center at UC Berkely.

Scientific research is starting to show that there is a very strong relationship between social-emotional learning and cognitive development and performance.

In her statement, she is advocating that a student's cognitive well-being is closely associated with their emotional well-being. Practicing empathy in the classroom allows the students to acquire a comfort level with the teacher. They realize that the teacher cares and they want to impress their mentor. The comfort level that is acquired will allow students to take risks with their learning. In other words, they will not be afraid to fail because they know that the teacher is understanding and compassionate. In this way, students can grow academically in meaningful ways and leave their comfort zone.

Another reason that it is important for teachers to practice empathy is to set an example for their students. While we are all born with compassion and understanding, they are skills that need to be practiced. They are also important 21st Century skills. If students see their teachers model empathy, they are more likely to be empathetic in their interactions with their peers. In this way, students are practicing a skill that will advance their futures.  

An astronaut has a mass of 80.0 kg. How far away from the center of the Earth would he need to be in order to have one half his weight on Earth?

According to the Universal Law of Gravitation, two bodies of masses m1 and m2, separated by a distance of "d," will attract each other with a force given by the following equation:

F= Gm1m2/d^2

Let m1 and m2 be the masses of the astronaut and the Earth and d be the distance between them. When the astronaut is on Earth's surface, the distance d = radius of Earth.

Let us say that the distance at which the astronaut will have half the weight he would on Earth's surface is d'. At this distance, the force of attraction would be half its original value.

Thus, F' = F/2 = Gm1m2/d'^2 = 1/2 (Gm1m2/d^2)

That is, d'^2 = 2d^2 

or d' = `sqrt(2)` d ~ 1.414 d

Thus, the astronaut will have to be about 1.414 times away from his position on Earth's surface for his weight to be half. Since the average radius of Earth is about 6,371 km, the astronaut will have to be about 9010 km away from the center of Earth.

Hope this helps. 

Does Brutus have power in Shakespeare's Julius Caesar?

Brutus does possess power in Shakespeare's play, the power that political influence wields; however, he loses this power because of his ineffective idealism.

Brutus is considered a very influential senator, and for this reason Cassius "courts" him in order to gain his support in the plot to assassinate Julius Caesar. For, in gaining the support of Brutus, Cassius knows that others joining in the conspiracy will then follow through with action. Inflamed by idealism, Brutus is convinced by Cassius that Caesar will become tyrannical if given the single rule of Rome, so he joins the conspiracy to assassinate Caesar, providing the murder plot's needed influence and impetus to action.

Having thus joined with the others, Brutus strikes the final stab into Julius Caesar on the Ides of March. Brutus's idealism is not in harmony with the raw rules of life, rules Cassius understands and about which he tries to convince Brutus. Brutus, then, becomes flawed in his assessment of human nature and its motivations. His flawed judgment is evinced in his address to the plebeians. While Brutus initially elicits their support as they shout "Live, Brutus! Live, live!" after he explains that he killed Caesar, not because he did not love him, but because he loved Rome more— 

Had you rather Caesar were living, and die all slaves, than that Caesar were dead, to live all free men? (III.2.21-22)

Nevertheless, the crowd is swayed soon after when Brutus permits Marc Antony to speak. At first, Antony walks onto the pulpit, carrying the bloody body of Julius Caesar, and Brutus offers to slay himself if the crowd demands it. Instead, the crowd continues to shout "Live, Brutus!"

It is not long before Antony creates doubt in the minds of the plebeians that Brutus and the others may not be honorable, but are instead the ones who are ambitious, not Caesar. His presentation of Caesar's mangled and bloody body informs the crowd of a vicious assault, one more demonstrative of hatred and self-interest. The plebeians assume these wounds were inflicted by exigent men, not noble idealists. Brutus has been lying, these wounds seem to indicate. Thus, Antony makes of Caesar a martyr, not a tyrant.

Brutus's tragic flaw is his misunderstanding of the base nature of man, which leads to his loss of influence and the increased power of the more pragmatic Marc Antony and demise of Cassius and Brutus.

Describe The Sweet Pea restaurant. Use text evidence from Bud, Not Buddy.

Bud describes The Sweet Pea restaurant when the band members take him there after meeting Herman E. Calloway at band practice.  They pull up to “a little house” in chapter 13, but the major description is found in chapter 14 of Bud, Not Buddy.  The first part of the description is the first sentence of chapter 14:

When we got into the restaurant I could see that it was someone’s living room that they’d set about ten card tables and some folding chairs in.

This quotation about The Sweet Pea restaurant shows us a bit about the setting of time:  the Great Depression.  People during that time did whatever they could to find a job, even if it is turning their living room into a restaurant using folding chairs and card tables.  Luckily for Bud and the band members, sometimes dives like this have the best food.  Bud notices this immediately because the smell of food was so wonderful Bud “could tell why folks were lining up to get in.”  In my opinion, it is Bud’s description of the olfactory image that is the most interesting:  a mixture of coffee and cider and pies and meat loaf.  Bud thinks it smells like heaven.  The next quotation describes some specifics about the atmosphere:

Every table but one was filled and there were five or six people standing in the doorway waiting to sit down.

Here is another quotation that reveals the popularity of The Sweet Pea restaurant as well as the importance of the band.  Even though there were people standing and waiting for a table, there is one table that remains unoccupied.  It has a sign on it that says “NBC.”  Steady Eddie tells bud that “NBC stands for ‘Nobody but Calloway.’”  This always allows the band a place to sit and eat food after practicing. 

In conclusion, it is important to note that it is within The Sweat Pea restaurant where Bud truly gets to know the members of Calloway’s band and begins to enjoy himself.  Sometimes the best parts of life can be found in unexpected places.

Which will feel hotter to touch: holding 10.0 g of aluminum at 95 degrees Celsius, or 10 g of lead at the same temperature? Assume each material is...

The substance that will release more heat as it cools down from 95 degrees Celsius to the skin temperature of 34 degrees Celsius will be hotter to touch. We can calculate the amount of heat released for each of the two materials, aluminum and lead, using specific heat capacity. The amount of heat required to raise the temperature of 1 gram of a substance by 1 degrees Celsius is known as its specific heat capacity. The specific heat capacities of aluminum and lead are 0.9 J/gm/K and 0.128 J/gm/K. Since the specific heat capacity of lead is less than aluminum, it will release less heat as it cools down.

We can also calculate the amount of heat released as the materials cool down by using the following equation:

Heat released = mass of substance x specific heat capacity x change in temperature

Heat released in the case of aluminum = 10 g x 0.9 J/g/K x (95 - 34) C = 549 J

Heat released in the case of lead = 10 g x 0.128 J/g/K x (95-34) C = 78.08 J

Thus, aluminum will release more heat than lead when it is held until it reaches the skin temperature. And it will feel hotter to touch as compared to lead.

How did Macbeth earn the respect of King Duncan in Act One?

Macbeth earns the respect of Duncan through his prowess on the battlefield. Duncan is facing an uprising by the rebel Macdonwald as well as a Norwegian invasion, and Macbeth and Banquo lead his forces against them. Duncan learns from a Sergeant returning from the fray that Macbeth met Macdonwald on the field and "unseam'd him from the nave to the chaps, And fix'd his head upon our battlements." Then Macbeth and Banquo defeated the Norwegian king, who had taken advantage of the internal strife by launching an invasion. Duncan responds to the Sergeant's account of the battle by exclaiming that Macbeth is his "valiant cousin" and a "worthy gentleman." The king then rewards his kinsman's loyalty and valor by naming him Thane of Cawdor, replacing the former holder of that title, who would be executed for his role in the rebellion. Macbeth's portrayal in this scene as a valiant, loyal thane makes his degeneration into a murderous, scheming monster late in the play all the more dramatic.

Why is Jack unable to kill the piglet in the curtain of creepers, and what does he resolve to do about it in Lord of the Flies by William Golding?

Jack is unable to kill the piglet because he has only just come from his very civilized and orderly world and has not yet tapped into any primal urges. But, he resolves that he will never falter again.

In Chapter One, the boys explore the island on which they now find themselves. As they climb the mountain, they encounter an environment of untamed nature: flowers, trees, rocks, creepers, bushes. In a thicket the boys hear the sound of little hooves and squealing; there they find a piglet caught in "a curtain of creepers." Jack, who has a knife, raises his arm up in order to drive this weapon into the piglet. But, he hesitates ever so slightly:

The pause was only long enough for them to understand what an enormity the downward stroke would be. Then the piglet tore loose ….They were left looking at each other and the place of terror. Jack’s face was white under the freckles.

Jack then makes an excuse for his trepidation, saying that he was only waiting for the right moment to stab the piglet, who was obviously trapped. But, he is cut off by Ralph, who fiercely criticizes him.

They knew very well why he hadn't: because of the enormity of the knife descending and cutting into living flesh; because of the unbearable blood.

Embarrassed, Jack resolves that "[N]ext time there would be no mercy." 

In this expository scene that begins the development of the theme of the inherent evil in man kept in check only because of controls established by civilized society, Jack's hesitation exemplifies his conditioning by civilization. For, it is only this conditioning which suspends his act of stabbing the piglet.

How can we make the separated salt from sea water better?

Common salt or sodium chloride (NaCl) is generally produced from sea water or ocean water. The other source is rock salt. Human beings have evaporated ocean water in large trenches for a very very long time and have obtained salts after water has been evaporated by solar energy.

Similar methods are used currently as well, in which sea water is stored in shallow trenches for a long time and salt is obtained after water has been evaporated. This salt is not yet fit enough for food processing and hence is further purified. In this process, dried salt is washed with a saturated solution of brine (NaCl in water). During this step, salt moves out of the aqueous phase, while the impurities are mixed with the aqueous phase. By repeating this process multiple times, we can obtain salt of very high purity.

Hope this helps. 

What are oncogenes? Can they cause cancer?

Exposure routes: Inherited as genetic information

Where found: Proto-oncogenes are genes found within the chromosomes of all eukaryotic (nucleated) cells and organisms.

At risk: Proto-oncogenes are universal among all eukaryotic cells and organisms, which include humans and all animals. Congenital mutations in some of these genes are associated with a significantly increased risk for certain cancers.

Etiology and symptoms of associated cancers: More than one hundred proto-oncogenes have now been recognized in cells. Most are involved in regulating movement through the cell cycle (regulation of chromosome replication followed by cell division). The cell cycle is characterized as having four phases: G1, which regulates events leading to deoxyribonucleic acid (DNA) replication; S, in which cell chromosomes replicate; G2, which regulates events leading to cell division; and mitosis, the period in which the chromosomes separate and the cell divides. Each phase is regulated by specific enzymes, signals, and other molecules, as well as suppressors that prevent movement through the phase. Many of the regulatory proteins involved in these events are encoded by proto-oncogenes. Not all proto-oncogenes are expressed in every cell, and the type of cancer that potentially develops is related to the particular oncogene that has undergone a mutation.

Proto-oncogenes are subdivided into four categories, each of which represents a particular set of steps that regulate the cell cycle: growth factors, growth factor receptors, signal mechanisms, and tumor suppressors/regulators of apoptosis (cell death).

Growth factors are small proteins that bind specific cell surface receptors and set in motion events that will result in cell division. Overproduction of growth factors may result in repeated cell division, setting the stage for development of cancer. For example, the PDGFB (commonly known as sis) oncogene, originally isolated from the simian sarcoma virus, encodes one of the protein chains that make up the platelet-derived growth factor. PDGFB is secreted by platelets and binds receptors on certain fibroblast cells. Overproduction of PDGFB may induce uncontrolled cell division, resulting in a sarcoma.

Growth factor receptors are cell surface proteins that bind specific growth factors. Each cell type expresses a particular form or forms of receptors, and the ability of any growth factor to stimulate a cell depends on expression of these surface molecules. Some of these receptor proteins are actually enzymes that, when activated, begin a series of signals within the cell, resulting in cell division. Certain mutations in the genes that encode these receptors may, in effect, cause a “short circuit” in regulation, resulting in loss of control and continuous movement of the cell through the cell cycle.

One example of such a receptor mutation is that of the
HER2/neu (also known as ERBB2) receptor protein expressed on certain breast cells. The HER2/neu protein is similar in its amino acid sequence to the human epidermal growth factor receptor molecule and is an example of a transmembrane enzyme that begins the signal transmission in the cell. A mutation in the HER2/neu proto-oncogene converts it into the HER2/neu oncogene (named for the neuroblastoma in which it was first identified). Overexpression of the HER2/neu protein is associated with the aggressive nature of certain forms of breast cancer. The basis for the chemotherapeutic action of Herceptin is its ability to inhibit the activity of the HER2/neu protein.

Signal mechanisms represent a series or cascade of enzymatic reactions that move the cell through the cell cycle and regulate cell division. At the molecular level, intermediates in this pathway are enzymes that activate DNA-binding proteins (DBPs), inducing gene expression. The RAS supergene family and the greater than one hundred proteins its members encode are examples of such inducers. RAS proteins are also called G proteins, reflecting their utilization of guanosine triphosphate (GTP) for their activity. Mutations in these genes may result in a continuous activating signal within the cell and uncontrolled cell division. Certain forms of colon and bladder cancers are the result of such mutations, and some forms of mutations are associated with mutations in the DNA-binding protein substrates for these RAS proteins. RAS gene mutations have been observed in nearly one-third of all cancers.

Tumor suppressors/regulators of apoptosis control steps at the end of the cell cycle. The proto-oncogenes that regulate apoptosis can either promote or inhibit cell death. The BCL2 gene family produces proteins that are pro-apoptosis and anti-apoptosis (the BCL2 gene itself inhibits apoptosis, and its overexpression has been implicated in cancers such as lymphoma). Proto-oncogenes and tumor suppressors provide the cell with the means not only to block division if chromosome replication is incomplete or if a mutation has occurred that could cause the cell to become cancerous but also to actually cause the cell to die. Tumor suppressors promote apoptosis and therefore are usually inactivated in cancers.

The first of the tumor suppressors to be discovered was the retinoblastoma RB1 protein, isolated in the 1980s. The RB1 protein regulates the steps that allow DNA replication to begin in the cell. The TP53 protein, named for its size, detects mutations that have occurred in DNA and induces repair of the DNA site or, if the mutation is too extensive, induces steps that culminate in the death of the cell.

As is true for other genes that regulate cell division, mutations in the genes associated with tumor suppression are associated with certain forms of cancer. For example, mutations in the

RB1 gene seem to predispose people for retinoblastoma. Mutations in the TP53 gene have been found in more than 50 percent of all forms of cancer. The ability of oncogenic viruses such as hepatitis B, the etiological agent for hepatocarcinoma, or the human papillomavirus, the agent for cervical carcinoma, to initiate cancer is related to their abilities to inactivate tumor suppressors. At least two dozen types of tumor suppressors were identified in the first decade of the twenty-first century.

Mutations at these sites may be caused as a result of infection by certain viruses or by exposure to carcinogens, most of which are also mutagens, chemicals that induce DNA mutations. In some cases, the mutation is congenital, the individual having been born with that specific mutation. Childhood retinoblastoma, for example, results from congenital mutations in the RB1 gene.

In some cases, it is not “simply” a point mutation in a proto-oncogene that leads to a cancer. Certain forms of the disease are known to result from chromosomal breaks and translocations, the movement of pieces of chromosomes from one site to another in the cell chromatin. The DNA in patients suffering from chronic myelogenous leukemia was found to possess a specific type of translocation. What became known as the Philadelphia chromosome is characterized by translocation of the ABL1 oncogene, on chromosome 9, into the region of the BCR oncogene on chromosome 22. The combined gene product disrupts the normal signaling mechanism in these cells, resulting in uncontrolled cell division. Inhibition of this activity is the basis of action for at least one type of antileukemic drug, imatinib mesylate (Gleevec), lending further support to this mutation as being the actual cause of chronic myelogenous leukemia.

Cancer, however, generally is not the result of any individual mutation. The molecules previously described regulate cell division, The difference between a benign growth and a true malignancy is the result of accumulated mutations over time. For example, a malignancy would require not only a mutation in the signal pathway but also, at a minimum, additional mutations in tumor-suppressor genes or in steps that inhibit cell death.

History: The evidence for existence of oncogenes dates to the early history of retroviruses, viruses with genomes of ribonucleic acid (RNA), which are copied into DNA following infection and which were found to be etiological agents for some forms of cancer. In the late nineteenth century, leukemia in animals was demonstrated to be transmissible using extracts from cells. However, leukemia was not considered to be a true cancer at the time. It was only when Peyton Rous demonstrated in 1911 that solid tumors in chickens sarcomas could be transmitted using cell-free extracts that scientists began to believe cancer, at least in animals, was associated with infectious agents. Eventually what became known as the Rous sarcoma virus (RSV) was isolated and identified with this disease in chickens.

As an increasing number of such tumor viruses, in which RNA was shown to be the genetic material, were isolated by the 1950s, the question that followed was how these viruses could change, or transform, cells from normal to cancerous. In 1958, Howard Martin Temin and Harry Rubin demonstrated that single virus particles could transform chicken cells. Further work by Temin indicated that it was possible to disrupt viral replication and transformation by adding inhibitors acting at the level of DNA. Temin proposed that such viruses act using a DNA intermediate and that they encode an enzyme that copies RNA into DNA, allowing what has become viral DNA to integrate into the cell chromosome. By the late 1960s Temin and David Baltimore independently discovered an enzyme, popularly known as reverse transcriptase, that carries out this function. Viruses that encode the enzyme have become known as retroviruses and include the RNA tumor viruses. Temin and Baltimore were each awarded the Nobel Prize in Physiology or Medicine in 1975.

The seemingly simplistic genetic structure of the RNA tumor viruses lent itself to determining which viral genes are associated with cancers. The discovery of a temperature-sensitive mutation in one of these genes led to the identification of the SRC gene in the Rous sarcoma virus, the first such oncogene to be discovered.

The SRC gene was shown to be required for transformation by the Rous sarcoma virus. However, strains of the virus that lacked that gene were found to replicate normally, suggesting the SRC gene was superfluous for the virus and may even have originated as genetic material extraneous to the virus. In 1976, J. Michael Bishop and Harold Varmus provided the answer. Creating DNA probes from transformation defective mutants of the Rous sarcoma virus, they found that normal avian cells contained cellular homologs of the viral SRC gene that is, a cellular proto-oncogene. The proto-oncogene product of the gene was subsequently shown to be an enzyme critical in the signaling pathway that regulates cell division.

Through the 1980s, an increasing number of cellular proto-oncogenes were identified, and evidence for their association with cancers was increasingly demonstrated. When carcinogens were used to transform cells growing in laboratory cultures, mutations were found in proto-oncogenes carried by these cells. Indeed, the only difference found between proto-oncogenes in normal cells and oncogenes expressed in cancer cells was often a mutation at a single site. For example, the RAS oncogene found in cases of bladder cancer differed from its counterpart in a normal cell at only one amino acid position, suggesting the origin of the cancer was a mutation at that site. The RAS product, as was the SRC product described above, was shown to be involved in the signaling pathway within the cell.

Bishop, J. Michael. How to Win the Nobel Prize. Cambridge: Harvard UP, 2003. Print.

Coffin, John, et al. Retroviruses. Plainview: Cold Spring Harbor Laboratory, 1997. Print.

Cooper, Geoffrey. Oncogenes. 2nd ed. Boston: Jones, 1995. Print.

Mitri, Zahi, Tina Constantine, and Ruth O'Regan. “The HER2 Receptor in Breast Cancer: Pathophysiology, Clinical Use, and New Advances in Therapy." Chemotherapy Research & Practice (2012): 1–7. Academic Search Complete. Web. 8 Dec. 2014.

Panno, Joseph. Cancer: The Role of Genes, Lifestyle, and Environment. Rev. ed. New York: Facts On File, 2011. Print.

Pecorino, Lauren. Molecular Biology of Cancer: Mechanisms, Targets, and Therapeutics. 3rd ed. Oxford: Oxford UP, 2012. Print.

Pelengaris, Stella, and Michael Khan. The Molecular Biology of Cancer. Malden: Blackwell, 2006. Print.

Vogelstein, Bert, and Kenneth Kinzler. The Genetic Basis of Human Cancer. New York: McGraw, 2002. Print.

Weinberg, Robert A. The Biology of Cancer. 2nd ed. New York: Garland Science, 2014. Print.

How did the relationship between Britain and its colonies change after the war, and why did Britain seek to change those relationships?

Since you don’t specify to which war you are referring, I assume you are referring to the French and Indian War. After the French and Indian War, the relationship began to change between Great Britain and the thirteen colonies.

One reason why the British established colonies was because they wanted to benefit economically from their colonies. After the French and Indian War, the colonies were becoming more expensive to operate, which meant the British were making less money from the colonies. Thus, the British wanted the colonists to share in some of the expenses of running the colonies because the colonists were benefiting from the rule of British. For example, the British army was protecting the colonists from attacks by the Native Americans. The British felt it was reasonable to have the colonists pay for housing the British troops that were in the colonies to protect them.

Another example of how the relationship changed was that the British began to pass tax laws that created taxes that the colonists had to pay. The Stamp Act and the Townshend Acts were examples of new tax laws. The colonists felt these tax laws were unfair because they didn’t have representatives in Parliament that could speak about or vote on these tax laws.

The changing relationship ultimately led the colonists to decide they needed to be free from British rule. This led to the writing of and adopting of the Declaration of Independence.

How do different cultures show importance in their religious beliefs?

There is a wide variety of ways in which a culture can demonstrate their religious beliefs.  At the far right of the spectrum are cultures in which the religious leaders also act as the political leaders.  This is known as a theocracy and an example would be modern-day Iran.  In this country, the religious law heavily dictates how people are expected to behave on a daily basis.  While most cultures are not this extreme, the legal codes of most cultures are also still heavily influenced by religion.  

A culture can also demonstrate its religion by the festivals and holidays that are celebrated throughout the year.  In some cases, these days will be periods of time when school, business, and government offices are closed.  

Another example of religion influencing culture can be seen in India where the caste system is closely tied to Hinduism and affects social class groupings.  

What is the difference between a vesicle and a lysosome?

Vesicles are cellular organelles that are composed of a lipid bilayer. They are used to transport materials through the inside of the cell.  Vesicles are formed naturally during the process of endocytosis and exocytosis. Vesicles can also function in metabolism and enzyme storage. There are four types of vesicles used by cells. These include: vacuoles, lysosomes, transport vesicles, and secretory vesicles. Lysosomes are cellular vesicles that contain digestive enzymes. They are used to break down food particles and to get rid of un-needed cellular particles. Lysosomes are like the garbage men of the cell. Their job is to take waste, digest it, and remove it from the cell. Lysosomes break down biomolecules engulfed by the cell. Examples include: nucleic acids, peptides, carbohydrates, and lipids.

What does a child learn in pre-school?

Pre-school (sometimes called pre-kindergarten or pre-K) is a combination of daytime childcare and early childhood education. Children may begin pre-school as young as three years, but more commonly at the age of four as preparation for entering kindergarten at five years. Pre-school helps children adjust to the environment outside of the home, learn to direct their attention for longer periods of time, develop social and fine motor skills, and begin learning some of the content they will encounter in primary school. Children in pre-school  might learn to sing the alphabet song, if their language has one, as well as counting. They may also learn to identify colors, shapes, animals, and natural phenomena like weather patterns. Pre-schools typically offer lessons in a "playtime" environment with group activities. Movement, singing, arts and crafts, and free play are also common in the curriculum.

Pre-school may be attended for a half day (in the morning or afternoon) or for a full day. As an example of how this time might be spent, a child may arrive at pre-school and sing a song, cut paper with safety scissors during craft time, have a snack, practice identifying shapes, make some animal sounds, ride a tricycle outside, and learn to wash their hands. Every pre-school differs a little bit in how they structure their schooling, but pre-school is generally intended to prepare a child mentally, socially, and physically for primary school. 

In Julie of the Wolves by Jean George, why does Miyax name the cowardly wolf "Jello"?

That is a super cool part of the book.  Me, personally, I would be terrified by hanging out with a bunch of wolves.  Miyax, though, is completely calm around the wolves.  She is calm because she learned to be that way from her father, but she is also calm because she needs the wolves to accept her and help her.  She is lost on the North Slope of Alaska, which is barren and basically devoid of food.  What she brought with her has run out, and Miyax left her village without her gun.  She needs the wolves to help feed her. As she begins to befriend the wolves, she begins assigning them names in order to better remember each wolf by.  She calls the leader Amaroq, and she gives the other wolves really rugged wolf names like "Silver" and "Nails."  The smaller, scared wolf she names "Jello" because when he approached Amaroq, he quivered and trembled in front of the alpha male.  The shaking wolf reminded Miyax of the dessert that her mother-in-law made.  

Next, Nails took Amaroq's jaw in his mouth and the leader bit the top of his nose. A third adult, a small male, came slinking up. He got down on his belly before Amaroq, rolled trembling to his back, and wriggled.

"Hello, Jello," Miyax whispered, for he reminded her of the quivering gussak dessert her mother-in-law made.

What does it mean to draw, in detail, significant parts of artwork?

Firstly, your question is not stupid. There is nothing wrong with needing help and there is a possibility that your instructor did not clearly detail what it is you need to do.

I'm not clear on what kind of piece you're doing, but it sounds like a large-scale project. Generally, when an artist is working on a very large piece -- e.g., a painting, sculpture, collage, mural -- she will do preliminary sketches and will work from those sketches to determine what the figures or objects in the piece will look like. That's what it sounds like your instructor is asking you to do. 

Think along the lines of the preliminary sketches that Michelangelo did before he began painting the ceiling of the Sistine Chapel. He drew all of the major figures and scenes, such as The Creation of Adam and The Fall of Man. From those sketches, he was able to understand how the bodies would look, what they would be doing, their expressions, as well as how they would be organized in the fresco. This is what it means to "draw in detail some of the significant parts of the artwork." Your instructor wants to see what you plan on doing and if it will work. He or she wants to see your ideas. 

I hope this helps. Best of luck on the project.

Why did Dill run away from home back to Maycomb?

Dill is a storyteller. When Scout finds him underneath her bed in chapter 14, he first tells her that he left Meridian because his step-father chained him up in the basement and left him to die. Once he pulled himself free from the chains, he left and found a small animal show where he was retained to wash a camel. When he came near Maycomb, he walked over and hid under Scout's bed. The real story, though, is that he took thirteen dollars from his mom's purse and took a train for most of the way. He walked about ten miles and hopped the back of a cotton wagon, too.

When Scout and Dill get some time alone away from adults, she asks him why he left his home. Dill had told her the previous summer that he and his new dad were going to build a boat together and things were happy. Unfortunately, Dill said that the boat never got built, but that his dad had only mentioned it. The fact is, Dill felt neglected. His mother seemed to be more interested in her new husband rather than Dill. The couple would go out on dates for a really long time and leave him all alone at home. Or, his parents would lock themselves in their room and not come out. Dill even feels like his parents are happier without him there, so he left. He decided to go to Maycomb where he would feel accepted and loved--not neglected like at home with his mother.

What is an important theme in "The Garden Party" by Katherine Mansfield?

An important theme in Mansfield's "The Garden Party" centers on individual identity.

One theme in Mansfield's short story concerns the formation of individual identity. Laura displays this theme throughout the narrative. At the story's outset, she seems comfortable with people from the working class. She finds the workers setting up the garden party to be "extraordinarily nice," preferring their company to the "silly boys she danced with and who came to Sunday night supper." Upon hearing of the worker's death, she finds it offensive to have the garden party. She is "astonished" at the banal reactions of Jose and her mother. Laura believes the party should be cancelled because of her identification with the working class.  

As the story progresses, Laura's working-class identity is not as evident. Laura is hesitant about taking the basket to the deceased worker's family, asking her mother if it is "a good idea." Laura is visibly uncomfortable when she visits the mourning family. She calls out for God's help and apologizes for her hat. As Laura stares at the worker's corpse, she struggles with even larger issues of identity:

What did garden-parties and baskets and lace frocks matter to him? He was far from all those things. He was wonderful, beautiful. While they were laughing and while the band was playing, this marvel had come to the lane. Happy. . . happy. . . All is well, said that sleeping face. This is just as it should be. I am content.

When she arrives back, readers are not sure what Laura's identity is. She "stammers" in a statement that might articulate thoughts about life. Like Laura's identity, that statement is muddled.

What Laura believes and how she will go about living her life are central questions at the end of "The Garden Party." They attest to the importance of the theme of identity in Mansfield's short story.

Read the following article by Marc Davis: Government Regulations: Do They Help Businesses? Do you think we have too much regulation of...

The EPA and FTC
Another frequent target of certain businesses is the Environmental Protection Agency. The disposal of waste materials, the restrictions on greenhouse emissions, pollutants and other substances harmful to land, water and atmosphere are now regulated by this government agency. Companies to which these rules apply have complained that the restrictions are costly and compromise profits. --Marc Davis

The perpetual give and take between big business and big government is always interesting to examine.  It is a symbiotic relationship in which each views the other as a necessary evil.  Businesses generally operate with the primary goal of making a profit.  They are often willing to allow the ends to justify the means in this pursuit of profit.  For this reason, I do not feel that there is too much regulation of business.  I would look at the need for environmental protection as a regulation that is necessary and proper to protect citizens from the abuses of big business.  The air we breathe, the water we drink, and animals and plants we eat are the property and privilege of all to enjoy.  A business does not have the right to harm or damage the resources that are vital to the survival of all of us.  The government has a responsibility to regulate businesses and their relationship to nature.  While the cost of operating in a responsible way towards the environment can be a financial burden for companies, it is justifiable for the government to ensure the protection of nature for the good of all.  For this reason, I feel that work of the Environmental Protection Agency is beneficial to society.

What is Barrett esophagus?

Related conditions:
Esophageal adenocarcinoma, gastroesophageal reflux disease (GERD), hiatal hernia

Definition:
Barrett esophagus is a condition in which some of the cells lining the esophagus (the tube that carries food to the stomach) are replaced with a different type of cell similar to those lining the intestines, a process called intestinal metaplasia. Rarely, these cells develop into cancer of the esophagus, specifically esophageal adenocarcinoma. This condition is named after Norman Barrett, who first described it in 1957.

Risk factors: Developing Barrett esophagus is linked to chronic heartburn and another common condition called gastroesophageal reflux disease (GERD). However, the chances of heartburn or GERD developing into Barrett esophagus are very small. Sometimes people who develop GERD also have a hiatal hernia, in which part of the stomach bulges through the diaphragm. This kind of hernia may trap acid in the esophagus and cause more damage, eventually leading to GERD and progressing into Barrett esophagus.

Etiology and the disease process: Normally, a round muscle (sphincter) near the bottom of the esophagus keeps stomach acid from washing back up into the esophagus. In people with GERD, some of the acid of the stomach leaks into the esophagus, possibly because of a weakness in the sphincter. In about 10 to 15 percent of these people, the acid changes the color and makeup of the cells lining the esophagus, making them darker than the normal esophagus tissue and more resistant to stomach acid, much like intestinal cells. Rarely, Barrett esophagus cells develop into a precancerous state called dysplasia. In some of these cases, dysplasia then develops into esophageal cancer.

Incidence: According to the National Digestive Diseases Information Clearinghouse, approximately 1.6 to 6.8 percent of people have Barrett esophagus. It is very uncommon in children; the average age of diagnosis is fifty-five. It is twice as common in men as in women. Caucasians and possibly Hispanics are more likely to develop this condition than those of other ethnic backgrounds.

Symptoms: Symptoms include chronic heartburn, chronic acid reflux, trouble swallowing or a feeling that something is stuck in the throat, weight loss, spitting up food, excessive burping, hoarseness, sore throat, and bleeding. Sometimes people with chronic heartburn will get some relief from their symptoms when they develop Barrett esophagus. The intestinal metaplasia may help protect the esophagus from the stomach acid because those cells are normally found in the intestines and are better able to withstand stomach acid.

Screening and diagnosis: Adults over the age of forty who have had chronic heartburn or acid reflux may be screened via endoscopy to see whether they have Barrett esophagus. However, screening for this disease is not commonly recommended, as an endoscopy is expensive and the rate of discovering the condition is very low. People who have no symptoms should not have an endoscopy just to see if they have this condition. Barrett esophagus can be diagnosed only by performing a biopsy on suspected tissue. There is no staging for Barrett esophagus.

Treatment and therapy: Treatment for Barrett esophagus involves avoiding further damage. Therapies that keep the acid in the stomach from moving up into the esophagus may include antacid-type medications or other medications that stop stomach-acid production, such as proton-pump inhibitors. Lifestyle changes, such as losing weight, stopping smoking, avoiding certain foods, and eating more fruits, vegetables, and vitamins, also help. Other ways to keep the acid in the stomach include eating smaller meals more often, wearing loose-fitting clothing, waiting two to three hours after eating before lying down, and elevating the head of the bed eight to ten inches. A type of surgery that reinforces the sphincter that keeps acid in the stomach may also help.

Ablative treatments for removing Barrett esophagus cells include photodynamic therapy, which kills the cells using a photosensitizing chemical called porfimer sodium and a laser, and radiofrequency ablation, which uses radio waves. However, removing the cells has not yet been proved to reduce the risk of developing esophageal cancer. Endoscopic ablation is usually recommended only when a patient has highly developed precancerous or already-cancerous cells.

There is no cure for Barrett esophagus other than surgically removing the esophagus. This type of surgery is only performed on those who have already developed esophageal adenocarcinoma or are at very high risk for developing it. In this surgery, the affected part of the esophagus is removed, and the stomach is brought up and attached to the nonaffected part of the esophagus.

Prognosis, prevention, and outcomes: Barrett esophagus may not cause any problems or symptoms in those who have it. It is only significant because it is a precursor to esophageal adenocarcinoma, but even those who have Barrett esophagus have approximately 0.5 percent chance of developing this type of cancer. Those who have been diagnosed with Barrett esophagus should be screened regularly, every one to three years, to ensure that the cells are not developing into cancer.

Some ways of attempting to prevent further damage to the esophagus are to eat a diet low in fat and high in fruits, vegetables, and fiber. Avoiding smoking and maintaining a healthy weight may also help.

Badash, Michelle. "Barrett's Esophagus." Rev. Daus Mahnke. Health Library. EBSCO, 7 May 2014. Web. 5 Sept. 2014.

"Barrett's Esophagus." Rev. G. Richard Locke and Joel Richter. National Digestive Diseases Information Clearinghouse. Natl. Insts. of Health, 20 Nov. 2013. Web. 4 Sept. 2014.

Falk, Gary W. "Barrett's Esophagus." The Esophagus. Ed. Joel E. Richter and Donald O. Castell. 5th ed. Malden: Blackwell, 2012. 509–39. Print.

Madell, Robin, and George Krucik. "Barrett's Esophagus and Acid Reflux." Healthline. Healthline Networks, 30 June 2012. Web. 4 Sept. 2014.

Owens, Scott R., and Henry D. Appelman. Atlas of Esophagus and Stomach Pathology. New York: Springer, 2014. Print.

Parker, James, and Philip M. Parker, eds. The Official Patient’s Sourcebook on Barrett’s Esophagus: A Revised and Updated Directory for the Internet Age. San Diego: Icon, 2002. Print.

Polsdorfer, Ricker. "Cancer InDepth: Esophageal Cancer." Rev. Mohei Abouzied. Health Library. EBSCO, 27 May 2014. Web. 5 Sept. 2014.

Shalauta, Saad R. “Barrett’s Esophagus.” American Family Physician 69.9 (2004): 2113–18. Print.

Sharma, Prateek, and Richard E. Sampliner, eds. Barrett’s Esophagus and Esophageal Adenocarcinoma. 2nd ed. Malden: Blackwell, 2006. Print.

Suppose you have 5 pith balls of unknown charges. You are told that A experiences a force of attraction near a glass rod rubbed with plastic, B...

Hello!

As I understand, the question is what charges these balls have. Each can be positively charged (+), negatively charged (-) or neutral (0).

It is well known that the same charges are repelled and the opposite are attracted. Also it is a well known phenomenon that neutral dielectric bodies are attracted to charged bodies, both positively and negatively. Note that neutral body is never repelled.

Also we need a starting point: what is the charge of a glass rod rubbed with plastic? The triboelectric series helps here, see the link. From it we know that glass becomes positively charged when rubbed by plastic.

1. C repels the glass rod (+) means C is also (+).

2. B repels A means they have the same charge and are not neutral.
A is attracted to the glass rod so A is (-) and B is (-).

3. D repels B so D is (-).

4. E is attracted to C (+) and D (-), so E cannot be (+) or (-), it is (0).

The answer: A is negative, B is negative, C is positive, D is negative and E is neutral.

In The Far and the Near, how does the engineer feel about the little house and the two women in the story?

In the story, the engineer views the two women and their little house as a "beautiful and enduring" inspiration to him; throughout his railroad career, he has always idealized the women and house as the epitome of innocence and perfection. The house has always had "an air of tidiness, thrift, and modest comfort" to it, and the women remind him of everything that is wholesome and good about the female gender.

The engineer had known much toil and trouble in his days. In his service, he had seen at least four tragedies unfold before his eyes. In looking back, he remembers the tormented and stunned faces of those facing death, as the train barreled towards them. He also remembers a body flung past his window after it was presumably hit by the train. Yet, throughout all these tragedies, the women and the house had always comforted him and given him the courage to continue in his work.

He remembers that he imbibed great happiness from seeing them every time his train passed by the women's house. So, he resolves to meet with them when his long years of service with the railroad is over. Alas, his meeting with the women is marred by reality. The women are not at all welcoming or pleasant. Instead, they are sullen, aloof, and hostile. When the engineer leaves them, he finds himself bereft of hope and joy. His path in life has suddenly become clouded and his future uncertain.

How does alcoholism affect a marriage/partnership?

Introduction

In the early 1930s, social workers in state hospitals reported their observations of the wives of alcoholic men, describing the wives as having anxiety, depression, and psychosomatic symptoms. The social workers suggested that such psychological symptoms were not caused by living with a chronic alcoholic; instead, the women who displayed such symptoms were using their marriages to alcoholic men to resolve their own neurotic conflicts. Furthermore, it was suggested that if the male alcoholic would decrease his drinking, the wife would suffer from the loss of a defense mechanism.

In the 1950s and 1960s, theory and treatment options shifted this view to one in which family members’ symptoms were viewed as a normal process in a high-stress environment with care similar to that required for a chronically ill spouse or partner. Continued research has focused upon the interactive process between alcoholics and others in close relationship with them.

Alcoholic Spouse/Partner Relationships

Addiction to alcohol is a relationship issue. Being married to or in a domestic partnership with an alcoholic places a strain on that relationship, causing the nonalcoholic partner to take on responsibilities that would not be expected in a nonalcoholic relationship. Studies find that marital or domestic relationships with alcoholics have a high degree of relationship dissatisfaction and that tension and verbal conflict are usually high.

A partner may assume a relational preoccupation that parallels the alcoholic’s obsessive preoccupation with alcohol, trying to convince the alcoholic mate to discontinue drinking. When this process characterizes the relationship, the nonalcoholic partner needs encouragement to emotionally abstain from participating in the partner’s alcoholic behavior.

Relationship Dynamics

Couple interaction can be significantly affected by alcoholism and alcohol-related behaviors. Alcoholism requires energy, not for long-term growth but for maintaining short-term stability. The developmental milestones that would be expected in a relationship are identified instead as developmental distortions.

A negative cycle may occur in which the spouse becomes more fearful as the alcoholic increases alcohol use, and may then respond with a greater focus on getting the alcoholic to stop drinking. The alcoholic experiences this through feeling over-scrutinized and pressured. The assumption, relative to the relationship conflict, is that if the drinking stops, the problems will stop. This attempt to manage the behavior of the other further deteriorates the relationship. Alcoholic behaviors become the primary factors in how the family system functions and is organized. In such cases, nonalcoholic partners may lose their sense of direction and identity as they attempt to survive in the high-stress environment and realize that their life has been structured around the alcoholic.

Under normal circumstances, a marital or domestic relationship exists to meet the basic needs of protection, shelter, and food of family members through a unified process. With heightened tension, such as when one partner is an alcoholic, changes occur in regulatory behaviors to ensure a relationship that accommodates the demands of alcoholism. If the partner of the alcoholic becomes anxious, the anxiety can escalate and spread to all family members. When this happens, the normal emotional connectedness that should be comforting becomes stressful. Eventually, family members begin to feel overwhelmed and out of control.

Family members who feel the greatest stress tend to accommodate others to alleviate familial tension. The person who accommodates the most, usually a spouse but sometimes a child, is attempting to absorb the anxiety present in others. This family member will become the most vulnerable to physical illness and depression, or even to alcoholism.

Relationship Violence

Although excessive use of alcohol has been associated with spouse (mostly wife) abuse, no evidence has found a causal relationship between alcoholism and family violence. However, factors that add stress to the family are associated with marital and partner violence, and excessive use of alcohol is a stress-producing factor. Conflict between the couple over drinking patterns also increases the potential that violence will be used to manage conflict.

Undesired sexual relations (including rape) may be forced by a partner after drinking. Substantial research shows that physical and sexual aggression in men is intensified by alcohol. A partner who is normally not aggressive can become aggressive or even violent when drinking heavily.

A national study found that the more often a spouse or partner was drunk, the greater the likelihood that physical violence would be a part of the relationship. In cases of extreme drinking by one partner who was almost always drunk, the likelihood of violence dropped to a lower level.

Intervention

Working with spouses and partners of alcoholics requires careful exploration. Many people have experienced relationships that are chaotic, unreliable, and emotionally confusing. Often the feelings of anger and resentment are not expressed for fear of exacerbating the alcoholic’s drinking or hindering his or her recovery. There may be repressed desires and dreams for the future that the nonalcoholic partner does not voice, such as buying a house or having more time together.

If a couple seeks therapy, and if one partner is a substance abuser, it is likely that the use of alcohol or the impact of alcohol-related behaviors will not be the focus of the relationship problems. This is to be expected because it is estimated that only one in four persons who abuse alcohol will seek treatment for their drinking problems. If the therapist does not demonstrate sensitivity to how alcoholism affects relationships, the issue may never become a part of treatment. It is generally believed that a combination of approaches, which includes both couples therapy and self-help approaches for alcoholism, will be necessary. A therapist should always assume the responsibility of helping the couple understand how alcoholism affects their relationship. Also, the therapist should help the couple understand what precipitates excessive drinking or what leads to a relapse.

Communication by the nonalcoholic partner will sometimes include diagnostic labeling as an attempt to encourage a partner to seek help. Labels such as being an alcoholic or being in denial carry certain stigmas, and it is only reasonable that persons with self-confidence will reject such labels. Relationships may have an underlying dynamic that represents a power struggle and one person’s attempt to assert control. A remark such as “Your problem is that you are in denial” may seem harmless when it is uttered, but tends to be perceived as judgmental.

Therapists in twelve-step programs usually focus on the processes that enable drinking. The goal is to help spouses or partners experience emotional insight and to identify enabling behaviors. Self-help support groups attempt to empower spouses and partners and to begin the process of establishing a meaningful and satisfying life, regardless of the partner’s alcoholism.

The National Council on Alcoholism and Drug Dependence in New York City provides five guidelines for persons dealing with an alcoholic. The organization’s advice is to recognize alcoholism as a disease, to learn as much as possible about alcoholism, to avoid becoming an enabler, to avoid home treatments, and to seek professional help for personal development.

Bibliography

Ackerman, R. Perfect Daughters: Adult Daughters of Alcoholics. Deerfield Beach: Health Communications, 2002. Print.

Freeman, Shelley MacKay. Paths to Recovery: Al-Anon’s Steps, Traditions, and Concepts. Virginia Beach: Al-Anon, 1997. Print.

Jay, Jeff, and Debra Jay. Love First. 2nd ed. Center City: Hazelden, 2008. Print.

Smith, Philip H., et al. “Women Ending Marriage to a Problem Drinking Partner Decrease Their Own Risk for Problem Drinking.” Addiction 107.8 (2012): 1453–61. SPORTDiscus with Full Text. Web. 29 Oct. 2015.

Watt, Toni Terling. “Marital and Cohabiting Relationships of Adult Children of Alcoholics.” Journal of Family Issues 23 (2002): 246–65. Print.

How does reading play a vital role in the development of the human mind, in reference to "There Is No Frigate Like a Book"?

Emily Dickinson's poem "There Is No Frigate Like a Book" is a perfect vehicle to expound upon the importance of reading to the development of the mind. Dickinson was a recluse, someone who seldom, if ever, left her home, but she developed her own mind through reading and shared this lovely little poem to remind us of its importance. The mind is like a muscle, and the more we read, the stronger our minds become. Reading is a way of developing knowledge and understanding of the world around us and within us. It brings us to places, times, and people we might otherwise never encounter, and it helps us to look within ourselves more deeply, too, as we compare and contrast others with ourselves. Often people will refer to reading as giving us windows and mirrors, to look outside and to look within.

In her poem, Dickinson contrasts reading with various forms of transportation, a "Frigate" (line 1), "Coursers" (line 3), and a "Chariot" (line 7). A frigate is a swift ship, a courser is a fast horse, and a chariot, of course, is an ancient form of transportation, thought to be speedy, although that is a relative term, as a practical matter. Any of these can take us somewhere else, to "Lands away" (line 2). But, Dickinson tells us, books do this even better because they are a "frugal" (line 7) means of travel, meaning that the cost of buying a book, or even borrowing one from a library or a friend, is far less than the cost of actual travel. There are no tolls to be paid, which makes the book a better bargain. Even people who are "the poorest" (line 5) can travel this way.

The last two lines are particularly interesting because I think they could be read two different ways:

How frugal is the Chariot
That bears a Human soul (lines 7-8).

I suggest that Dickinson could be speaking of the soul (and the mind) of the reader or the writer in this passage. If a book is a chariot, then it surely bears the soul of the writer. But if the chariot is bearing, that is carrying, the reader, then it is the soul of the reader that is contemplated here.  This ambiguity enriches the poem, I think. The soul and mind of a reader are being developed through the act of reading, and for the writer, it is the writing that is a form of human development of the soul and mind.

The act of reading develops our minds, taking us to settings we could otherwise never experience, allowing us to experience other times, places, and people, and allowing us to contemplate how wonderfully different they may be as well as how soothingly similar they are. Every time we go on a voyage in a book, we are developing our minds and our souls, as Dickinson clearly understood.

What are DNA and RNA?

Structure and Functions

Each human being is a biologically unique individual. That uniqueness has its basis in one’s cellular makeup. Appearance derives from the arrangement of cells during fetal development, size depends on the cells’ ability to grow and divide, and the function of organs depends on the biochemical function of the individual cells that constitute each organ. The functions of cells depend on the types and amounts of the different proteins that they synthesize. The substance that holds the information that determines the structure of proteins, when they should be produced, and in what amounts is deoxyribonucleic acid (DNA).

DNA is the molecule of heredity, and as a child receives half of his or her DNA from each biological parent, each individual is the product of a mixture of information. Therefore, while children resemble their parents, they are unique. Each cell in an individual’s body (except for the sex cells) has a complete set of genetic information contained in the chromosomes of the cell’s nucleus. Human cells have forty-six chromosomes (twenty-three pairs). Each chromosome is a single piece of DNA associated with many types of proteins. The major function of DNA is to store, in a stable manner, the information that is the “blueprint” for all physiological aspects of an individual. Stability is one of the key attributes of DNA. An information storage molecule is of little use if it can be altered or damaged easily. Another key characteristic of DNA is its ability to be replicated. When a cell divides, the information in the DNA must be replicated so that each of the two new cells can have a
complete set.

Stability, the ability to be replicated, and the ability to store vast amounts of coded information have their basis in the structure of DNA. DNA is a long, incredibly thin fiber. The chromosomes in some cells would be as long as a foot or more if they were fully extended. The shape of the DNA molecule can be imagined as a long ladder whose rails are chains of two alternating molecules: deoxyribose (a sugar) and phosphate (an acid containing phosphorus and oxygen). The steps of the ladder are made of pairs of organic bases, of which there are four types: adenine (A), guanine (G), thymine (T), and cytosine (C). Adenine always pairs up with thymine to form a step in the ladder (A-T), and guanine always pairs with cytosine (C-G). This complementarity of base-pairing is the basis for DNA replication and for transferring information from DNA out of the nucleus and into the cytoplasm. Finally, the whole DNA molecule is twisted into a stable right-handed spiral, or helix. Because there is no restriction on the sequence in which the base pairs appear along the molecule, the bases have the potential to be used as a four-letter alphabet that can
encode information into “words” of varying lengths, called genes. Each information sequence, or gene, holds the information needed to synthesize a linear chain of amino acids, which are the building blocks of proteins. The information encoded in the base sequences of DNA determines the quantities and composition of all proteins made in the cell.

Under certain conditions, DNA can be separated lengthwise into two halves, or denatured, by breaking the base pairs so that one of each pair remains attached to one sugar-phosphate chain and the other base remains attached to the other sugar-phosphate chain. Because this forms two strands of DNA, whole DNA is usually referred to as being double-stranded. Such separation rarely happens by accident because of the extreme length of DNA. If any area becomes denatured, the rest of the base pairs hold the molecule together. In addition, an area of denaturation will automatically try to renature, since complementary bases have a natural attraction for each other. As stable as these traits make it, DNA must be capable of being duplicated so that each newly divided cell has a complete copy of the stored information. DNA is replicated by breaking the base pairs, separating the DNA into two halves, and building a new half onto each of the old halves. This is possible because the complementarity rule (A pairs with T, and C pairs with G) allows each half of a denatured DNA molecule to hold the information needed to construct a new second half. This is accomplished by special sets of proteins that separate the old DNA as they move along the molecule and build new DNA in their wake.

All the information needed to produce proteins is located in the DNA within the nucleus of the cell, but all protein synthesis occurs outside the nucleus in the cytoplasm. An information transfer molecule is required to copy or transcribe information from the genes of the DNA and carry it to the cytoplasm, where large globular protein complexes called ribosomes take the information and translate it into the amino acid structure of specific proteins. This information transfer molecule is ribonucleic acid (RNA). Many RNA copies can be made for any single piece of information on the DNA and used as a template to synthesize many proteins. In this way, the information in DNA is also amplified by RNA. RNA also participates in the synthesis of proteins from the genetic information. RNA resembles one half of a DNA molecule and is usually referred to as being single stranded. It consists of a single chain of alternating sugars and phosphates with a single organic base attached to each sugar. The sugar in this case is ribose, similar to deoxyribose, and the bases are identical to those in DNA with the exception of thymine, which is
replaced by a very similar base called uracil (U).

There are four major types of RNA. Messenger RNA (mRNA) is responsible for the transfer of information from the DNA sequences in the nucleus to the ribosomes in the cytoplasm. Ribosomal RNA (rRNA) interacts with dozens of proteins to form the ribosome. It aids in the interaction between mRNA and the ribosome. Transfer RNA (tRNA) is a group of small RNAs that helps translate the information coded in the mRNA into the structure of specific proteins. They carry the amino acids to the ribosome and match the correct amino acid to its corresponding sequence of bases in the mRNA.

The first step in producing a specific protein is the accurate copying or transcription of information in a gene into information on a piece of mRNA. There are specific sets of proteins that separate the double-stranded DNA in the immediate vicinity of a gene into two single-stranded portions and then, using the DNA as a template, build a piece of mRNA that is a complementary copy of the information in the gene. This is possible because RNA also uses organic bases in its structure. The A, C, G, and T of the single-stranded portion of DNA form base pairs with the U, G, C, and A of the mRNA, respectively. The complementary copy of mRNA, when complete, falls away from the DNA and moves to the cytoplasm of the cell.

In the cytoplasm, the mRNA binds to a ribosome. As the ribosome moves down the length of the mRNA, the tRNAs interact with both the ribosome and the mRNA in order to match the proper amino acid (carried by the tRNAs) to the proper sequence of bases in the mRNA. The order of amino acids in the protein is thus determined by the order of bases in the DNA. Achieving the correct order of amino acids is critical for the correct functioning of the protein. The order of amino acids in the chain determines the way in which it interacts with itself and folds into a three-dimensional structure. The function of all proteins depends on their assuming the correct shape for interaction with other molecules. Therefore, the sequence of bases in the DNA ultimately determines the shape and function of proteins.

Another class of RNA is involved in translation regulation, by a process called RNA interference, or RNAi. The two types of RNA in this class are short interfering RNA (siRNA) and micro RNA (miRNA). SiRNA is a double-stranded molecule of twenty to twenty-five base-pairs in length, whereas miRNA is single stranded and consists of nineteen to twenty-three nucleotides. SiRNA and miRNA become incorporated in a protein complex known as the RNA-induced silencing complex (RISC). The RISC-associated siRNA targets a specific sequence in its target mRNA, and when bound to the mRNA causes destruction. MiRNA bound RISC binds to the mRNA and inhibits translation of that mRNA; in this case, however, the mRNA is not destroyed. RNAi plays a role in diverse cellular functions such as cell differentiation, fetal development, cell proliferation, and cell death. It is also involved in pathogenic events such as viral infection and certain cancers.

Disorders and Diseases

When the normal structure of DNA is altered (a process called a mutation), the number of proteins produced and/or the functions of proteins may be affected. At one extreme, a mutation may cause no problem at all to the person involved. At the other extreme, it may cause devastating damage to the person and result in genetic disease or cancer.

Mutations are changes in the normal sequence of bases in the DNA that carry the information to build a protein or that regulate the amount of protein to be produced. There are different types of mutations, such as the alteration of one base into another, the deletion of one or many bases, or the insertion of bases that were not in the sequence previously. Mutations can have many different causes, such as ultraviolet rays, X rays, mutagenic chemicals, invading viruses, or even heat. Sometimes mutations are caused by mistakes made during the process of DNA replication or cell division. Cells have several systems that constantly repair mutations, but occasionally some of these alterations slip by and become permanent.

Mutations may affect protein structure in several ways. The protein may be too short or too long, with amino acids missing or new ones added. It might have new amino acids substituting for the correct ones. Sometimes as small a change as one amino acid can have noticeable effects. In any of these cases, changes in the amino acid sequence of a protein may drastically affect the way the protein interacts with itself and folds itself into a three-dimensional structure. If a protein does not assume the correct three-dimensional structure, its function may be impaired. It is important to note that how severely a protein’s function is affected by a mutation depends on which amino acids are involved. Some amino acids are more important than others in maintaining a protein’s shape and function. A change in amino acid sequence may have virtually no effect on a protein or it may destroy that protein’s ability to function.

If a mutation occurs that affects the regulation of a particular protein, that gene may be perfectly normal and the protein may be fully functional, but it may exist in the cell in an improper amount—too much, too little, or even none at all. It is important to note that the overproduction of a protein, as well as its underproduction or absence, can be harmful to the cell or to the person in general. The genetic disease known as Down syndrome, for example, is the result of the overproduction of many proteins at the same time.

The term “genetic disease” is used for a heritable disease that can be passed from parent to child. The mutation responsible for the disease is contributed by the parents to the affected child via the sperm or the egg or (as is usually the case) both. The parents are, for the most part, quite unaffected. Because all creatures more complex than bacteria have at least two copies of all their genes, a person may carry a mutated gene and be perfectly healthy because the other normal gene compensates by producing adequate amounts of normal protein. If two individuals carrying the same mutated gene produce a child, that child has a chance of obtaining two mutant genes—one from each parent. Every cell in that child’s body carries the error with no normal genes to compensate, and every cell that would normally use that gene must produce an abnormal protein or abnormal amounts of that protein. The medical consequences vary, depending on which gene is affected and which protein is altered. The following are two specific examples of genetic diseases in which the connection between specific mutations
and the disease states are well documented.

Sickle cell disease is a genetic disease that results from an error in the gene that carries the information for the protein beta globin. Beta globin is one of the building blocks of hemoglobin, the molecule that binds to and carries oxygen in the red blood cells. The error or mutation is a surprisingly small one and serves to illustrate the fact that the replacement of even a single amino acid can change the chemical nature and function of a protein. Normal beta globin has a glutamic acid as the sixth amino acid in the protein chain. The mutation of a single base in the DNA changes the coded information such that the amino acid valine replaces glutamic acid as the sixth position in the protein chain. This single alteration causes the hemoglobin in the red blood cell to crystallize under conditions of low oxygen concentration. As the crystals grow, they twist and deform the normally flexible and disk-shaped red blood cells into rigid sickle shapes. These affected cells lose their capacity to bind and hold oxygen, thereby causing anemia, and their new structure can cause blockages in small capillaries of the circulatory system, causing pain and widespread organ damage. There is no safe and effective treatment or cure for this condition.

Phenylketonuria (PKU) is caused by a mutation in the gene that controls the synthesis of the protein phenylalanine hydroxylase (PAH). There are several mutations of the PAH gene that can lead to a drastic decrease in PAH activity (by greater than 1 percent of normal activity). Some are changes in one base that lead to the replacement of a single amino acid for another. For example, one of the most common mutations in the PAH gene is the alteration of a C to a T that results in amino acid number 408 changing from an arginine to a tryptophan. Some mutations are deletions of whole sequences of bases in the gene. One such deletion removes the tail end of the gene. In any case, the amino acid structure of PAH is altered significantly enough to remove its ability to function. Without this protein, the amino acid phenylalanine cannot be converted into tyrosine, another useful amino acid. The problem is not a shortage of tyrosine, since there is plenty in most foods, but rather an accumulation of undesirable products that form as the unused phenylalanine begins to break down. Since developing brain cells are particularly sensitive to these
products, the condition can cause mental retardation unless treated immediately after birth. While there is no cure, the disease is easily diagnosed and treatment is simple. The patient must stay on a diet in which phenylalanine is restricted. Food products that contain the artificial sweetener aspartame (NutraSweet) must have warnings to PKU patients printed on them since phenylalanine is a major component of aspartame.

Perspective and Prospects

Genetics is a young science whose starting point is traditionally considered to be 1866, the year in which Gregor Mendel published his work on hereditary patterns in pea plants. While he knew nothing of DNA or its structure, Mendel showed mathematically that discrete units of inheritance, which are now called genes, existed as pairs in an organism and that different combinations of these units determined that organism’s characteristics. Unfortunately, Mendel’s work was ahead of its time and thus ignored until rediscovered by several researchers simultaneously in 1900.

DNA itself was discovered in 1869 by Friedrich Miescher, who extracted it from cell nuclei but did not realize its importance as the carrier of hereditary information. Chromosomes were first seen in the 1870’s as threadlike structures in the nucleus, and because of the precise way they are replicated and equally parceled out to newly divided cells, August Weismann and Theodor Boveri, in the 1880’s, postulated that chromosomes were the carriers of inheritance.

In 1900, Hugo de Vries, Karl Correns, and Erich Tschermak von Seysenegg—all plant biologists who were working on patterns of inheritance—independently rediscovered Mendel’s work. De Vries had in the meantime discovered mutation around 1890 as a source of hereditary variation, but he did not postulate a mechanism. Mendel’s theories and the then-current knowledge of chromosomes merged perfectly. Mendel’s units of inheritance were thought somehow to be carried on the chromosomes. Pairs of chromosomes would carry Mendel’s pairs of hereditary units, which, in 1909, were dubbed “genes.”

At that point, genes were still a theoretical concept and had not been proved to be carried on the chromosomes. In 1909, Thomas Hunt Morgan began the work that would provide that proof and allow the mapping of specific genes to specific areas of a chromosome. The nature of a gene, or how it expressed itself, was still a mystery. In 1941, George Beadle and Edward Tatum proved that genes regulated the production of proteins, but the nature of genes was still in debate. There were two candidates for the chemical substance of genes; one was protein and the other was the deceptively simple DNA. In 1944, Oswald Avery proved in experiments with pure DNA that DNA was indeed the molecule of inheritance. In 1953, James D. Watson and Francis Crick, using the work of Rosalind Franklin, elucidated the chemical structure of the double helix, and soon after, Matthew Meselson and Franklin Stahl proved that DNA replicated itself. By the end of the 1950’s, RNA was being implicated in protein synthesis, and much of the mechanism of translation was postulated by Marshall Nirenberg and Johann Matthaei in 1961.

Craig Mello and Andrew Fire were awarded the 2006 Nobel Prize in Physiology or Medicine for their discovery of siRNA and for their research on the RNAi system. In 1993, Victor Ambros was the first person to describe miRNA. Both siRNA and micro RNA have possible therapeutic use. Clinical trials involving siRNA and miRNA are in progress. Examples are the use of siRNA in the treatment of macular degeneration, an age-related eye disorder, and the use of miRNA in the treatment of chronic hepatitis C. The major barriers to the use of these molecules are inefficient delivery to target cells and off-target effects.

The concept of heritable genetic disease is also a relatively recent one. The first direct evidence that a mutation can result in the production of an altered protein came in 1949 with studies on sickle cell disease. Since then, thousands of genetic diseases have been characterized. The advent in the 1970’s of recombinant DNA technology, which allows the direct manipulation of DNA, has greatly increased the knowledge of these diseases, as well as demonstrated the genetic influences in maladies such as cancer and behavioral disorders. This technology has led to vastly improved diagnostic methods and therapies while pointing the way toward potential cures.

Bibliography

Campbell, Neil A., et al. Biology: Concepts and Connections. 6th ed. San Francisco: Pearson/Benjamin Cummings, 2008. This classic introductory textbook provides an excellent discussion of essential biological structures and mechanisms. Its extensive and detailed illustrations help to make even difficult concepts accessible to the nonspecialist. Of particular interest are the chapters constituting the unit titled “The Gene.”

Drlica, Karl. Understanding DNA and Gene Cloning: A Guide for the Curious. 4th ed. Hoboken, N.J.: Wiley, 2004. This book for the uninitiated explains the basic principles of genetic mechanisms without requiring knowledge of chemistry. The first third is especially good on the fundamentals, but the remainder may be too deep for some readers.

Frank-Kamenetskii, Maxim D. Unraveling DNA: The Most Important Molecule of Life. Translated by Lev Liapin. Rev. ed. Reading, Mass.: Addison-Wesley, 1997. This very readable book provides an excellent history of the discovery of DNA. Also describes the nature of DNA and discusses genetic engineering and the ethical questions that surround its use.

Glick, Bernard, Jack J. Pasternak, and Cheryl L. Patten. Molecular Biotechnology: Principles and Applications of Recombinant DNA. 4th ed. Washington, D.C.: ASM Press, 2010. Explores the scientific principles of recombinant DNA technology and its wide-ranging use in industry, agriculture, and the pharmaceutical and biomedical sectors.

Gonick, Larry, and Mark Wheelis. The Cartoon Guide to Genetics. Rev. ed. New York: Collins Reference, 2007. An effective mixture of humor and fact makes this book a nonthreatening reference on genetics. Presented using historical context, it covers DNA and RNA structure and function and much more.

Gribbin, John. In Search of the Double Helix. New York: Bantam Books, 1985. Gribbin is a renowned science writer who is capable of explaining complex subjects in a way that anyone can understand. In this book, he goes from Charles Darwin’s theories to quantum mechanics in his rendition of the history of the discovery of DNA. Very readable.

Hofstadter, Douglas R. “The Genetic Code: Arbitrary?” In Metamagical Themas: Questing for the Essence of Mind and Pattern. New York: Basic Books, 1985. While only a thirty-page chapter in a large book, this piece by Hofstadter is an excellent and thought-provoking explanation of transcription and translation written for the nonscientist.

Micklos, David A., Greg A. Freyer, and David A. Crotty. DNA Science: A First Course. 2d ed. Cold Springs Harbor, N.Y.: Cold Springs Harbor Press, 2003. Text that combines an introductory discussion of the principles of genetics, DNA structure and function, and methods for analyzing DNA with twelve laboratory experiments that illustrate the basic techniques of DNA restriction, transformation, isolation, and analysis.

Nicholl, Desmond S. T. Introduction to Genetic Engineering. 3d ed. New York: Cambridge University Press, 2008. A valuable textbook for the nonspecialist and anyone interested in genetic engineering. It provides an excellent foundation in molecular biology and builds on that foundation to show how organisms can be genetically engineered.

Paddison, Patrick J., and Peter J. Voght. RNA Interference. New York: Springer, 2008. A comprehensive book about the field of RNA interference that includes detailed and updated mechanistic descriptions of the RNAi process.

Watson, James D., and Andrew Berry. DNA: The Secret of Life. New York: Knopf, 2004. Nobel Prize-winning scientist Watson guides readers through the rapid advances in genetic technology and what these advances mean for modern life. Covers all aspects of the genome in a readable fashion.