Apentix/AP Biology/Unit 6: Gene Expression and Regulation/Question
AP Biologyhardmcq1 pt

Telomeres shorten gradually in most human somatic cell lineages yet stay stable through germline divisions. Which statement explains the difference?

A.Germline cells express telomerase, an enzyme that extends chromosome ends using its own internal RNA template
B.Somatic chromosomes lack protective repetitive ends entirely
C.Somatic cells copy their DNA faster, leaving larger gaps
D.Somatic chromosomes fuse end to end to halt further erosion

Explanation

Core Concept

Lagging strand synthesis cannot replicate the extreme end of a linear chromosome, so each division trims the telomere slightly. Telomerase is a reverse transcriptase carrying an RNA subunit that serves as the template for adding repeat units onto the 3' end, restoring full length. Germline and stem cells maintain telomerase expression while most somatic cells silence it. Expression level, not replication speed, produces the contrast.

Correct Answer

AGermline cells express telomerase, an enzyme that extends chromosome ends using its own internal RNA template

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