Chromosome Structure Basics

Steps:

• Recall that chromosomes consist of DNA packaged with proteins into chromatin.
• Identify that each chromatid contains a single DNA molecule coiled around histones to form nucleosomes.
• Evaluate options against standard definitions: chromosomes in interphase are unreplicated (one chromatid), telomeres protect both ends, centromeres contain DNA, and histones organize DNA.
• Select the option accurately describing DNA-histone interaction.

Why D is correct:

• Each chromatid's DNA forms a double helix coiled into nucleosomes with histone proteins, enabling compact chromosome structure as per chromatin packaging principles.

Why the others are wrong:

• A: Chromosomes at interphase start with one chromatid (unreplicated DNA); two chromatids form after S phase.
• B: Telomeres are at both ends of each chromatid, not one, to cap linear chromosomes.
• C: Centromeres contain DNA sequences for kinetochore attachment and sister chromatid cohesion.

Final answer: D