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CH10-Chromosomes,-Mitosis,-and-Meiosis-part-04 - SVNAPSIS...

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Unformatted text preview: SVNAPSIS - HOMOLOGOUS C’SOMES ALIGN DURING PROPHASE I . Ma'i'er'nal Figure 10-14 228 simr chr'omai'ids Pa‘ier'nal sis'rer' chr'oma'rids Synapfonemal complex Ma‘ier'nal sis‘ier' chr'oma‘iids (b) TEM of a synaptonemal complex, (a) A 3-D model of a tetrad with a complete Synaptonemal complex CROSSING OVER is a PROCESS of GENETIC RECOMBINATION During crossing over' nonsisi'er' chr'omai'ids break and exchange corresponding segmen'i's of DNA ' I Sister Chlasma’ra _ ._ chromatids °Chiasma (pl. chiasma‘i'a) cr'iss-cr'ossed regions of Te'rr'ad where nonsisi'er' chromai'ids exchanged DNA -Gene‘iic r'ecombinct‘iion — formation of new gene combina‘iions by mixing pa’rer‘nal and ma’rer'nal DNA °In humans, crossing over occurs an average of 1-3 Times per' homologous pairs of chromosomes 11 TIMING of MEIOSIS in The LIFE CYCLE - ANIMALS In animals, meiosis leads directly To game’re forma'iion — Figure 10—17 p 230 _ _ Game'res are fhe only GameTogeneSIs — germ line cells are haploid cells and do no’r The only cells Tha’r undergo meiosis (gametes (n) undergf furil‘" dM‘im '5perma1'ogenesis — male game1'ogenesis germ cell (2n) m>4 sperm (n) ' -Oogenesis — female gameTogenesis @ Fertilization germ cell (2n) mB‘OSlS > 1 ovum (n) ‘ Zygole (2n) Mitosis Muliicellular diploid Soma'ric cells are organism diploid clones of zygo‘i'e (2n) produced by mifosis (a) Animals TIMING of MEIOSIS in The LIFE CYCLE — MOST FUNGI and PROUSTA Unlogllu'larlor Organism remains haploid mllltlcelIUIaf Throughout most of lifecycle haploid organism in) Mitosis Mitosis Gamat'es (n) Fertilization Zygoi'e is fhe only diploid stage and immedia‘i‘ely divides by meiosis To produce haploid cells Zygme (2”) (b) Simple eukaryotes 12 TIMING of MEI OSIS in The LIFE CYCLE PLANTS and ALGAE! .r' - ,_.‘ 1: fi-. -:.|.. '1”- ':¢|. '5‘; Al‘rer‘nai'ion O'F genera'l'ions - mul'ricellular' diploid s‘l'age al1'er'na1'es wi'rh a mul'ricellular' haploid sfage Spores don'l‘ fuse bu‘l' divide by mifosis To produce game’rophyfe Sporophy'l'es produce haploid spores by meiosis Game'l'ophy'l'es produce haploid game’res by mifosis Mitosis Sporophyte (2n) (multicellular diploid organism) (c) Plants, some algae, and some fungi 13 Fertilization Zygote (2 n) ZygoTe produces a mulficellular sporophyfe by mi’rosis ...
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CH10-Chromosomes,-Mitosis,-and-Meiosis-part-04 - SVNAPSIS...

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