Question
Biology Question on cell cycle and cell division
In meiosis crossing over is initiated at :
A
Leptotene
B
Zygotene
C
Diplotene
D
Pachetene
Answer
Pachetene
Explanation
Solution
The Pachytene stage is characterized by the formation of the synaptonemal complex. This allows the exchange of genetic material between two homologous chromosomesby crossing over process. Initiation of crossing over occurs in the pachytene stage of prophase I of meiosis.
In meiosis crossing over is initiated at the pachytene stage.
- During Leptotene, chromosomes become gradually visible under a microscope. The chromosome compaction continues through this stage.
- During Zygotene, chromosomes start pairing together, known as synapsis.
- During Pachytene, bivalent chromosomes clearly appear. During this stage, the crossing over is initiated.
- During the Diplotene stage, the dissolution of synaptonemal takes place.
Therefore, the correct answer is Option A - Pachytene