When a Cell Loses Telomerase Activity, What is the Predicted

Question

When a cell loses telomerase activity, what is the predicted effect?
A)Telomeres will increase slightly with each cell division.
B)After 30-50 divisions, the cell will show signs of senescence and then die.
C)An immune stem cell will increase white blood cell production.
D)A normal somatic cell will gain the ability to divide indefinitely.
E)The cell will die immediately.

Accepted Answer

Telomerase is an enzyme that adds DNA sequence repeats ("TTAGGG" in all vertebrates) to the 3' end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. This enzyme is essential for maintaining the length of telomeres, thereby ensuring the chromosome's stability and integrity. In the absence of telomerase activity, telomeres become progressively shorter with each round of cell division. Eventually, when telomeres shorten to a critical length, the cell can no longer divide and enters a state known as senescence. If the cell does not undergo programmed cell death (apoptosis) at this point, it may continue to live in a senescent state for some time before dying. This process typically occurs over a span of 30-50 divisions in human cells, which is known as the Hayflick limit.