Multiple Choice
During which stage of meiosis does crossing over (genetic recombination between homologous chromosomes) primarily occur?
28
views
4. Genetic Mapping and Linkage
Crossing Over and Recombinants
Multiple Choice
In what stage of meiosis does crossing over (homologous recombination) primarily occur?
A
Metaphase I
B
Prophase I (specifically pachytene)
C
Prophase II
D
Anaphase I
Verified step by step guidance1
Recall the stages of meiosis I: Prophase I, Metaphase I, Anaphase I, and Telophase I, and understand that crossing over involves the exchange of genetic material between homologous chromosomes.
Focus on Prophase I, which is subdivided into leptotene, zygotene, pachytene, diplotene, and diakinesis stages, where homologous chromosomes pair and recombine.
Identify that crossing over specifically occurs during the pachytene stage of Prophase I, when homologous chromosomes are fully synapsed and exchange segments of DNA.
Understand that Metaphase I involves alignment of homologous pairs on the metaphase plate, but no crossing over happens here; similarly, Prophase II and Anaphase I do not involve crossing over.
Conclude that the primary stage for crossing over (homologous recombination) is Prophase I, specifically during the pachytene substage.
Related Videos
Related Practice
