notes-Meiosis - MeiosisAlternation of diploid and haploid A...

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Meiosis- Alternation of diploid and haploid A sexual life cycle involves an alternation of diploid (2n) and haploid (1n) generations Fertilization produces diploid cells by fusing to haploid cells Meiosis is the process of deriving haploid cells from diploid cells Alternation of generations- organism goes through both haploid and diploid stages Haplontic life cycle- organism is a haploid and the only diploid stage is the zygot Diplontic life cycle- the organism is diploid and the only haploid stage is gametes Spore becomes gametophyte by mitosis which then makes gametes; fertilization fuses the gametes to make a zygote which becomes a sporophyte which then becomes a sporangium which undergoes meiosis to get the spore again ; cycle repeats Alternation of generations- eukaryotic cells; mosses; fern; grasses; trees Diplontic- meiosis directly produces gametes; no mitosis Haplontic- fungi; most of the life has only one chromosome; zygote does not undergo mitosis and immediately undergoes meiosis to make spores Only one sperm allowed into ovum Fertilization- union of nuclei of two cells (sperm and egg) Meiosis more complicated than fertizliation Start off with diploid nucleus- 2 chromosomes of each type 23 pairs of chromosomes
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This note was uploaded on 12/08/2010 for the course BIS 2A taught by Professor Grossberg during the Fall '08 term at UC Davis.

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notes-Meiosis - MeiosisAlternation of diploid and haploid A...

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