Q.2. Describe the different phases of meiotic prophase – I. Mention the chromosomal events during each stage. ​

QUESTION:

Describe the different phases of meiotic prophase – I. Mention the chromosomal events during each stage.

During the prophase – I, genetic recombination and variation in sexually reproducing entities takes place due to the events of this stage.

Leptotene:–

Chromosomes are long, thin and slender.Chromatin network exposes and threads appear clear.The diploid number of chromosomes.

Zygotene:–

Similar chromosomes turn intimately associated.Synapse is exact hence pairing is not just between chromosomes, but corresponding individual units.Chromosomes appear thicker and shorter.

Pachynema:–

Synaptic chromosomes become intimately related.Thick and short pair of chromosomes.Cross over occurs, Chiasmata visible clearly.

Diplotene:–

Homologous chromosomes start detaching from each other.Chiasmata tends to shift away from chromosomes, termed as thermalization of chiasmata.Chromosomes detach out, but it is an incomplete separation.Nucleolus and nuclear membrane start to fade.

Diakinesis:–

The bivalents are randomly distributed after further condensation.The paired chromosomes separate completely.Terminalisation of chiasmata is almost concluded.The disappearance of the nucleolus and nuclear membrane.