Crossing over (genetic recombination) occurs during which stage of meiosis?
A
Prophase I (specifically pachytene)
B
Metaphase I
C
Anaphase II
D
Telophase I
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1
Recall the stages of meiosis I: Prophase I, Metaphase I, Anaphase I, and Telophase I, and understand the key events that occur in each stage.
Focus on Prophase I, which is subdivided into leptotene, zygotene, pachytene, diplotene, and diakinesis, and note that homologous chromosomes pair up and exchange genetic material during this phase.
Understand that crossing over, or genetic recombination, specifically occurs during the pachytene substage of Prophase I, where homologous chromosomes are tightly paired and exchange segments of DNA.
Recognize that Metaphase I involves alignment of homologous chromosome pairs at the metaphase plate, but no crossing over occurs here.
Note that Anaphase II and Telophase I are later stages where chromosomes separate, but crossing over has already taken place earlier during Prophase I.