BRAINCAKEAnaphase 1
In anaphase I the homologous chromosomes in each bivalent are separated. The spindle fibres shorten and pull one whole chromosome of each pair towards one pole and its homologue towards the opposite pole.
The key point is that the centromeres do not divide in anaphase I. Each chromosome still consists of two sister chromatids joined at its centromere, and it moves as a unit. This is the main difference from anaphase of mitosis (and from anaphase II), in which the centromeres divide and sister chromatids are separated.
Any chiasmata formed in prophase I are resolved as the homologues pull apart, so chromatids that crossed over separate, carrying their exchanged sections with them.
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Key terms in this lesson
- centromere
- The region of a chromosome that joins sister chromatids together and to which spindle fibres attach during cell division.
More in Meiosis and Sexual Reproduction
- Formation of Gametes
- Meiosis
- Prophase 1
- Metaphase 1
- Telophase 1
- Meiosis 2
- The Importance of Meiosis
- Chromosome Mutation
All 28 lessons in Meiosis and Sexual Reproduction · All Edexcel AS-level Biology topics