Meiosis

Meiosis

Early prophase I

Prophase I Metaphase I Anaphase I

Telophase IMetaphase IIAnaphase IITelophase II

Late telophase II

Independent assortment of chromosomes – homologous chromosomes line up on the equator independently, as a result all gametes are different

Crossing over – mixes the alleles of genes on homologous pairs of chromosomes

Meiosis increases variation by…

1. Independently sorting one of each chromosome pair into each gamete. Gametes can therefore contain a wide variety of different combinations of alleles.

2. Exchanging some alleles on the same chromosome with different alleles on the homologous chromosome by crossing over. These chiasmata produce further variation in the combination of alleles in gametes.

3. Reduce the chromosome number in gametes enabling fertilisation to produce further mixing of alleles from parents in sexual reproduction.