Question

question 12 of 26

which statement best describes a chromosome?

a. a single molecule of tightly coiled dna
b. multiple molecules of dna wrapped around each other
c. the part of a dna molecule that is wrapped around a cluster of proteins
d. a segment of a dna molecule that codes for a specific protein

Explanation:

Define a chromosome

A chromosome is a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. In eukaryotic cells, a single chromosome consists of one continuous, extremely long double-stranded DNA molecule that is highly folded and coiled around histones (proteins) to fit inside the nucleus. This relates directly to our understanding of DNA Structure.

Evaluate Option A

Option A states: "A single molecule of tightly coiled DNA." This is biologically accurate for a single eukaryotic chromosome (in its unreplicated state), which consists of one long double-helix DNA molecule tightly packaged and coiled.

Evaluate Option B

Option B states: "Multiple molecules of DNA wrapped around each other." This is incorrect because a single chromosome does not consist of multiple independent DNA molecules wrapped around one another.

Evaluate Option C

Option C states: "The part of a DNA molecule that is wrapped around a cluster of proteins." This describes a nucleosome, which is the basic structural unit of chromatin, rather than an entire chromosome.

Evaluate Option D

Option D states: "A segment of a DNA molecule that codes for a specific protein." This is the definition of a gene, not a chromosome. A chromosome contains hundreds to thousands of genes.

Answer:

• A. A single molecule of tightly coiled DNA (Correct answer)
• B. Multiple molecules of DNA wrapped around each other
• C. The part of a DNA molecule that is wrapped around a cluster of proteins
• D. A segment of a DNA molecule that codes for a specific protein