The image above shows the first division of meiosis, Meiosis I. The initial cell is a diploid cell. Notice that the homologous pairs are being separated, but not the attached chromatids. When Meiosis I is complete...
The image above shows the second division of meiosis , Meiosis II. Notice now, the attached chromatids are being separated. At the end of Meiosis II, meiosis is complete and 4 UNIQUE gametes have been created.
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In the GIFs of Meiosis I and II, you might have noticed a mixing of the colors in the chromosomes. That is the result of crossing over. Crossing over occurs early in Meiosis I and is the exchange of DNA between homologous chromosomes. The original chromosomes still contain each of their genes, but have most likely swapped different alleles for many of their genes. Because of crossing over, each gamete will be unique in that it inherits individual, genetically unique chromosomes while still carrying one of every gene.
Unit 4: Genetics & Heredity
Unit 4: Genetics & Heredity
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