The overproduction, lack of production or production of the wrong enzyme can cause cells to do what?

The exact effect depends strongly upon the enzyme in question, but in general we can say that these malfunctions could cause the cell to operate less efficiently, or to die. 

Let's say the enzyme in question is helicase, which assists in DNA replication by "unzipping" the double helix via breaking the hydrogen bonds between the nitrogenous bases:

• Overproduction of helicase could result in excessive splitting of strands outside of the normal conditions in which this process is allowed; in one of the sources below, observations suggest this can lead to illegitimate recombination, which is the fusing of two nonhomologous DNA strands. This would almost certainly lead to loss of function and fidelity in the organism.


• Lack of production of helicase would lead to inability to catalyze this reaction, which may prevent the organism from undergoing mitosis successfully.


• Production of the wrong enzyme would depend upon what "wrong" enzyme was produced, but the effects would also include those that occur due to a lack of production, since no helicase is being made.