Telomeres protect chromosome ends during DNA replication

Steps:

• Recall that DNA replication shortens chromosomes slightly each cycle due to the end-replication problem.
• Identify telomeres as repetitive, non-coding DNA sequences at chromosome ends.
• Understand telomeres act as buffers, sacrificing themselves to prevent essential genes from being lost.
• Eliminate options unrelated to replication protection, confirming D as the match.

Why D is correct:

• Telomeres cap chromosome ends, preventing the loss of genetic information during incomplete replication of linear DNA, as defined by the end-replication problem in molecular biology.

Why the others are wrong:

• A: Chromosome movement to poles is handled by the mitotic spindle, not telomeres.
• B: Sister chromatids are held by cohesin proteins, not telomeres.
• C: Chromatid length identity is ensured by semi-conservative replication, not telomeres.

Final answer: D