What is the role of telomerase in DNA replication?

Telomerase plays a crucial role in DNA replication by extending the ends of chromosomes, known as telomeres.

Telomerase is a unique enzyme that is involved in the replication of DNA, specifically at the ends of chromosomes. These ends, known as telomeres, are sequences of repetitive DNA that protect the rest of the chromosome from degradation. However, due to the way DNA replication works, these telomeres shorten each time a cell divides. This is where telomerase comes into play.

Telomerase is able to add more of the repetitive DNA sequence to the ends of the chromosomes, effectively extending the telomeres. This is a crucial process because if the telomeres become too short, the cell can no longer divide and becomes senescent or dies. Therefore, telomerase helps to maintain the length of the telomeres, allowing cells to continue dividing and thus promoting cell longevity.

The activity of telomerase is not constant in all cells. In most somatic (body) cells, telomerase activity is low or absent, leading to progressive shortening of telomeres over time. This is thought to contribute to the ageing process. However, in certain cells, such as stem cells and most cancer cells, telomerase activity is high. This allows these cells to divide indefinitely, which is beneficial for stem cells in tissue repair, but problematic in the case of cancer cells, as it contributes to their uncontrolled growth.

In summary, telomerase plays a vital role in DNA replication by extending the telomeres at the ends of chromosomes. This helps to prevent the loss of important genetic information during cell division and promotes cell longevity. However, the activity of telomerase can also have implications for ageing and cancer.