Question

Assertion (A): Every cell’s telomeres act as an ageing clock.

Reason (R): Telomeres are protective nucleotide sequences that are present at the ends of chromosome and they get shorter as cell divide.

Options

• Both A and R are true and R is the correct explanation of A.

• Both A and R are true but R is not the correct explanation of A.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is the correct explanation of A.

Explanation:

The assertion is true because telomeres dictate the lifespan of a cell lineage, functioning effectively as an internal cellular ageing clock. The reason is also true and serves as the correct explanation because every time a cell divides, a small portion of these protective terminal nucleotide sequences is lost due to the end-replication problem. Once the telomeres shorten to a critical threshold, the cell can no longer divide, triggering cellular senescence or biological ageing.