Cells must control gene expression so thatA) their genes will be expressed only when needed. B) their genes will always be expressed. C) their...

The correct response is A. In gene expression, the genetic
information is translated by protein synthesis into a protein, a functional gene
product. However, cells control the expression of genes producing the proteins it needs,
when it needs them and allowing for differentiation in the body amongst the various
cells contained therein. An example is the hormone insulin, which is a protein vital for
the regulation of blood glucose levels. Its expression allows for the excess blood
glucose to enter the cells to be utilized in respiration and for the rest to be stored
as glycogen. Gene expression allows for hormones to be released when needed, for cyclins
which regulate the cell cycle to be produced and for important protein products to be
present to adapt to an ever changing environment outside and within a
cell.