Question

In the diplotene stage, why do bivalents appear in different shapes?

Answer 1

Bivalents:

1. Bivalents are paired chromosomes that are formed during the prophase of meiosis 1.
2. Each bivalent consists of two chromosomes and four chromatids, where one chromosome comes from each parent.
3. After the synaptonemal complex is dissolved in diplotene, the recombined homologous chromosomes of the bivalents separate from each other except at the sites of crossovers.
4. They then form X-shaped structures called chiasmata.

The shape of bivalents:

1. The number of chiasmata depends on the length of the chromosomes which determines the shape of a bivalent.
2. As a result, the bivalents appear as loops, circles, crosses, etc.
3. They further undergo condensations.