Question

What are the sub-stages of Prophase-I?
Write few characteristics of those stages in brief.​

Answer 1

It is divided into five sub steps which are as follows-

1. Leptotene-

•Replication of chromosomes condense in this.

• Chromosomes become visible gradually under light microscope.

• Compaction of chromosome continuous throughout leptotene.

2. Zygotene-

• Pairing between homologous chromosomes that means synapsis process begins from here.

• Synaptonemal complex helps in the process of synapsis.

• It appears like tetrad or bivalent.

3. Pachytene-

• In this tedras is more clearly visible.

• Recommendation nodules appears in this.

• In the homologous chromosomes Clcrossing over occurs between non-sister chromatids.

4. Diplotene-

• Dissolution of Synaptonemal complex occurs in this.

• Appearance of the chiasmata starts and Bivalents starts to separate.

• Even it can last for months/years in some vertebrate females.

5. Diakinesis-

• It is the last step of Prophase-I.

• In it lastly nucleus disappears.

• Break down if nuclear envelope occurs in this step.

Answer 2

Explanation:

Prophase I is divided into five sub-phases: leptotene, zygotene, pachytene, diplotene and diakinesis. Another sub-phase called preleptonema is sometimes recognized prior to leptonema. Chromosomes are not distinguishable because of their thinness. Sex chromosomes are often seen in heterochromatic bodies.