On chromosome 14 is a gene that makes part of an enzyme called telomerase, which is involved in controlling the process of aging in our cells. In a sense, genes are immortal. We inherit genes from our parents, who inherited them from their parents and so back through an unbroken chain for four billion years, since the first life on earth. But in our lifetimes, the genes in our bodies do indeed deteriorate and our bodies age as a result. The tips of the chromosomes can often fray, and this is one of the things that telomerase is involved in repairing. So telomerase is necessary for ensuring the immortality of the genetic line.