Evaluation · Q38
Q.Explain the mechanism of crossing over.
Tamil Nadu DgeTextbookSubjectiveImportance★★★★★
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Start your 14-day free trial to unlock the full solution →Step 1. Synapsis begins at zygotene: the two homologous chromosomes align side by side along their whole length, forming a bivalent.
Step 2. Tetrad formation follows: each homolog duplicates into two sister chromatids held at a shared centromere, so the bivalent now has four chromatids.
Step 3. The crossover occurs at pachytene: non-sister chromatids make contact at chiasmata (organised by the synaptonemal complex), break and rejoin reciprocally, exchanging equal segments. …
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