Biology 1001A Lecture Notes - Lecture 9: Chromosome, Sexual Reproduction, Zygote
6 Dec 2017
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Document Summary
Chemicals and radiation can damage dna which can lead to mutations. Sexual reproduction is a biological generator of variation. Meiosis is a powerful biological generator of variation, that evolution needs. For speciation to occur, there needs to be variation amongst the two-differing species. Human zygotes do not do recombination, but plants/ fungi preform recombination in. In animal life cycles, the zygote divides by mitosis meiosis. Any arrangement of maternal and paternal components is possible at the poles (due to recombination. One way meiosis generates diversity is crossing over, they also align independently and the last way is recombination. Zonkeys are usually infertile. (zebras 2n=46, and donkeys are 2n=62) The zonkeys are infertile because the zebra and donkey chromosomes will fail to form proper homologous pairs during meiosis 1, during. When genes are close together in location, the chance that they will be separated during crossing over are lower. Disjunction: the failure of tetrad disjointment in meiosis 1.
