What role does telomerase play in a cell?

Telomerase is an enzyme that plays a crucial role in maintaining the length of telomeres, which are the protective caps at the ends of linear chromosomes. Every time a cell divides, a portion of the telomere is lost due to the inability of DNA polymerase to completely replicate the very end of the DNA strand. As a result, with each cell division, telomeres gradually shorten, which can eventually lead to cellular aging and senescence.

Telomerase counters this shortening by adding repetitive nucleotide sequences to the telomeres, effectively extending their length. This activity is particularly important in stem cells and germ cells, allowing them to divide without losing telomeric DNA. In many somatic cells, telomerase activity is low or absent, which is why these cells have a limited number of divisions before they undergo senescence.

Understanding the function of telomerase is also significant in the context of cancer, where many cancer cells reactivate telomerase to maintain telomere length, allowing for unlimited cell division and contributing to tumor growth. Thus, the primary role of telomerase in a cell is to maintain the length of telomeres, ensuring genomic stability and longevity of the cell's ability to divide.