Question

Explain the stages of prophase I of meiosis.

Answer 1

The prophase I of meiosis occurs in the following stages:

1. Leptotene- This phase is the start of prophase-I. It is marked by the condensation of the chromosomes.

2. Zygotene- In this phase the homologous chromosomes start pairing up, called the synapsis. The synaptonemal complex starts building up. This complex is required to hold the homologous chromosomes at a place close to each other. Bivalent chromosomes are visible at this stage.

3. Pachytene- In this stage, this non-sister chromatids of homologous chromosomes exchange their parts, the process is called the crossing over. The attachment point of the crossing-over of the non-sister chromatids is called chiasma.

4. Diplotene- The crossing-over process is completed by this stage. The homologous chromosomes remain attched at the point of chiasma.

5. Diakinesis- The homologous chromosomes start to separate and synaptonemal complex disappears. The nuclear membrane also disappears.