DNA, RNA, Chromosomes, and Genes
Are all genes in a genome used by an organism?
No, not all genes are used by an organism all the time. Since protein synthesis is an energy intensive cellular process, proteins are not produced unless they are needed for a specific cell function. For example, before a human has reached adult height, cells are continually producing human growth hormone, a protein that encourages bone and muscle growth. However, at a certain age (it varies by individual) the gene will become dormant and will no longer produce growth hormone.