A cross-over in meiosis is an exchange of genetic material between what structures?

• A. Sister chromatids of the same chromosome
• B. Centromeres of homologous chromosomes
• C. Non-sister chromatids of homologous chromosomes
• D. Ribosomal RNA and transfer RNA

Answer: (C)

Verified step by step guidance

1. Understand the process of meiosis: Meiosis is a type of cell division that reduces the chromosome number by half, creating four haploid cells. It involves two rounds of division: meiosis I and meiosis II.
2. Identify the role of homologous chromosomes: During meiosis I, homologous chromosomes (pairs of chromosomes, one from each parent) line up together. Each chromosome consists of two sister chromatids.
3. Define cross-over: A cross-over is a process where non-sister chromatids of homologous chromosomes exchange genetic material. This occurs during prophase I of meiosis I, leading to genetic recombination.
4. Differentiate between sister and non-sister chromatids: Sister chromatids are identical copies of a single chromosome, connected by a centromere. Non-sister chromatids belong to homologous chromosomes and are not identical.
5. Recognize the significance of cross-over: The exchange of genetic material between non-sister chromatids increases genetic diversity in the resulting gametes, which is crucial for evolution and adaptation.