Biology 1001A Chapter 9.3: Genetic Recombination in Eukaryotes- Meiosis (Chapter 9.3)
Document Summary
Animals have a diploid life cycle in which the diploid phase in multicellular and the haploid phase is unicellular. Plants and some fungi have an alternating-generations life cycle in which either haploid or diploid phases are multicellular and both of which divide by mitosis. The diploid sporophytes are produced by fertilization, and divisions of the spores formed by meiosis. Most fungi exhibit a haploid life cycle in which the haploid phase is multicellular and the diploid phase is limited to a single cell produced by fertilization which then immediately undergoes meiosis. In animals, the products of meiosis are haploid gametes. The diploid phase of the life cycle is then restored when one gamete fuses with another at fertilization. In plants, meiosis occurs in some of the cells of the diploid sporophytes and produces a generation of haploid spores. These spores then divide by mitosis to produce multicellular gametophytes. Gametes are formed from mitotic division of specific sporophyte tissues.
