Question

A human muscle cell has the same DNA inside its nucleus as a human nerve cell, even though these cells are very different in structure and function. How is this possible?

Answer 1

This is because in every cell, certain genes are expressed more than others. For instance, in a cell making up a human muscle cell, the cell would only express the genes appropriate to muscle function and not express the genes appropriate to that of a nerve cell. The opposite would be true for a nerve cell, likewise.