Deoxyribonucleic acid (DNA) is made up of two long polynucleotide chains wrapped around each other to form what is referred to as a double helix. Each chain is called a DNA strand held together by a sugar-phosphate backbone from which four bases extend.
The base portion on one strand binds to a complementary one on the other strand. They are held together by hydrogen bonds between them to form base pairs. The sequence of these four bases- adenine (A), cytosine (C), guanine (G) and thymine (T) encode the information stored in the DNA .
A copy of our DNA is replicated in every cell of our body to enable it to express the genetic code embedded in it. This is accomplished by an enzyme called DNA helicase which is responsible for unzipping the DNA strands to expose the nucleotides so that the nucleotide bases, where information is encoded, can be used as templates for replication.
The DNA expresses itself by controlling the type of protein a cell can make. Even though every cell has a full complement of genes, only certain genes can express themselves. This makes it possible for a single fertilised egg to differentiate into many types of cells.
DNA transmits genetic information that is copied accurately to the next generation. Through a process called genetic recombination, segments of different chromosomes exchange places with each other, creating new sequences of genetic material which can produce new proteins. If changes occur in the DNA sequence, these can be inherited by the next generation.
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