Telomerase's role in preventing telomere shortening

Steps:

• Telomerase adds nucleotides to telomeres, protecting chromosome ends during DNA replication.
• Without telomerase, telomeres shorten progressively with each cell division.
• Shortened telomeres activate DNA damage responses, leading to cellular senescence.
• In bone marrow stem cells, this halts proliferation, impairing blood cell production.

Why C is correct:

• Telomeres shorten without telomerase, causing replicative senescence where cells permanently stop dividing (Hayflick limit).

Why the others are wrong:

• A: Reduced stem cell division decreases, not increases, lymphocyte production.
• B: Telomerase absence limits unlimited division, preventing tumor growth.
• D: Stem cell failure reduces overall cell production and total count.

Final answer: C