Which structures contain identical copies of DNA?

• A. Homologous chromosomes
• B. Nucleosomes
• C. Sister chromatids
• D. Centromeres

Answer: (C)

Verified step by step guidance

1. Understand the structure of a chromosome: A chromosome is a long DNA molecule with part or all of the genetic material of an organism. During cell division, chromosomes are duplicated to ensure each new cell receives a complete set of genetic information.
2. Learn about sister chromatids: After DNA replication, each chromosome consists of two identical copies called sister chromatids. These are joined together at a region called the centromere.
3. Differentiate between homologous chromosomes and sister chromatids: Homologous chromosomes are pairs of chromosomes (one from each parent) that are similar in shape, size, and genetic content but are not identical. In contrast, sister chromatids are identical copies of a single chromosome, formed during DNA replication.
4. Explore the role of nucleosomes: Nucleosomes are structural units of a chromosome, consisting of a segment of DNA wound around a core of histone proteins. They help in packaging DNA into a compact, dense shape, but do not contain identical copies of DNA themselves.
5. Identify the correct structure: Based on the definitions, sister chromatids are the structures that contain identical copies of DNA, as they are the result of DNA replication of a single chromosome.