In which types of cells does telomerase remain active?

Telomerase is an enzyme that plays a crucial role in maintaining the length of telomeres, which are the protective caps at the ends of chromosomes. In most somatic (body) cells, telomerase is not active, leading to progressive shortening of telomeres with each cell division. This shortening is associated with aging and limits the number of times a cell can divide.

In contrast, telomerase remains active in germ cells, specifically in sperm and egg cells. The activity of telomerase in these cells is essential for ensuring that the telomeres are maintained during the numerous divisions that occur as the germ cells develop. This maintenance is critical because it helps preserve genetic stability and allows for proper reproduction. When sperm and egg cells unite during fertilization, they contribute to the formation of a zygote that has longer telomeres, which is associated with healthy development.

While muscle cells, nerve cells, and somatic cells generally do not have active telomerase, the germ line cells—sperm and egg cells—demonstrate prolonged telomere length due to the presence of telomerase, highlighting the importance of this enzyme in reproduction and genetic inheritance.