Question

Crossing over is the exchange of genetic material between

• A. Non-sister chromatids of the homologous chromosomes
• B. Sister chromatids of the homologouse chromosome
• C. Chromatids of non-homologous chromosome
• D. The genes those are completely linked

Answer 1

Answer: (A)

Non-sister chromatids of the homologous chromosomes

In meiosis I, during pachytene, crossing over occurs between the non-sister chromatids of the homologous chromosomes. The exchange of genetic material (DNA) between the non-sister chromatids of the homologous chromosomes is known as crossing over. It leads to the recombination of genetic material which involves a mutual exchange of the corresponding segments of non-sister chromatids of homologous chromosomes. It takes place by breakage and reunion of chromatid segments.