Question

Choose the correct answers from the alternatives given :
Synapsis is characteristic of

• A. leptotene
• B. zygotene
• C. pachytene
• D. diakinesis

Answer 1

The correct option is B zygotene

• Zygotene is the second stage of the prophase 1 of meiosis 1
• The chromosomes of the cell starts to pair during the prophase. During this phase the homologous chromosomes pair with each other this is called synapsis, the chromosomes pair in a zipper fashion.
• These form bivalents where the 2 pairs of sister chromatid are paired together.
• Leptotene is the first stage of prophase 1 where the chromosome condense and form thread like structures.
• Pachytene is the 3rd stage followed by zygotene, here crossing over of the non sister chromosomes takes place where the genetic material is exchanged at the site of formation of chiasmata.
• diplotene is the 4th stage where the non sister chromosomes where they have crossed over starts to move away from each other but remain connected at the site of chiasmata.
• Diakinesis is the last phase of prophase 1 where the chromosome tetrad is clearly visible with chiasmata and the overlapping chromosomes. At the end of this phase the nuclear membrane has disappeared and the cell is ready to enter the metaphase 1.
• Therefore the correct answer is option 'zygotene'.