Biology 1001A Lecture 8: - evolutionary advantages of gene duplication - products of meiosis in animals vs. plants, fungi and algae - timing of meiosis in vertebrate life cycles - main differences between meiosis and mitosis - characteristics of homologou
20 Oct 2015
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9. 1 mechanism of genetic recombination genetic recombination requires: two dna molecules that differ from one another, a mechanism for bringing the dna molecules into close proximity, and a collection of enzymes to cut , Most recombination occurs between regions of dna that are similar, but not identical in the. Meiosis occurs only in eukaryotes that reproduce sexually and only in organisms that are at least diploid that is, organisms that have at least two representatives of each chromosome. Dna replicates and the chromosomal proteins are duplicated during the premeiotic interphase, producing two copies, the sister chromatids, of each chromosome. During prophase i of the first meiotic division (meiosis i), the replicated chromosomes condense and come together and pair as the spindle forms in the cytoplasm. While they are paired, the chromatids of homologous chromosomes undergo recombination by breaking the covalent bonds of the dna backbones, matching complementary sequences on nonsister chromatids, exchanging the ends, and restoring the bonds.
