Meiotic Recombination: The Essence of Heredity

Neil Hunter1

  • 1Howard Hughes Medical Institute, Department of Microbiology & Molecular Genetics, Department of Molecular & Cellular Biology, Department of Cell Biology & Human Anatomy, University of California Davis, Davis, California 95616.

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Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I,...
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Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
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