BRAINCAKEGenetic Causes of Variation - Meiosis and Chance
During meiosis 1 crossing over leads to each chromatid being different.
During meiosis 1 the 23 homologous chromosomes (in humans) line up on the equator side by side arranged in a random order.
Which chromosomes go to which daughter cell is a matter of chance.
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Key terms in this lesson
- meiosis
- Nuclear division that halves the chromosome number, producing four genetically different haploid daughter cells for use as gametes.
- chromatid
- One of two identical copies of a chromosome, joined by a centromere, formed after DNA replication.
- homologous chromosomes
- A pair of chromosomes, one from each parent, that carry the same genes at the same loci but may carry different alleles.
- crossing over
- The exchange of sections of DNA between non-sister chromatids of homologous chromosomes during prophase I of meiosis, creating genetic variation.
More in Classification and Evolution
- Comparative Anatomy
- Comparative Biochemistry
- Types of Variation
- Genetic Causes of Variation - Mutation
- Environmental Causes of Variation
- Discontinuous Variation
- Continuous Variation
- Normal Distribution
All 36 lessons in Classification and Evolution · All OCR AS-level Biology topics