Kitajima_week4_HO2pp1 - BSC 2011 Kitajima week 4 Plan for...

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BSC 2011 Kitajima week 4 1 • Tue 10/21 - alternation of generations (pp. 242, 576- • Wed 10/22 - Angiosperm flowers, pollination, development of fruits, seeds, and seedlings (pp. 772-780) • Thu 10/23 - Signal transduction, phytochrome, seed germination and seedling development (pp. 788-806) • Fri 10/24 NO CLASS – HOME COMING • Tue 10/28 - Adaptation and acclimation to abiotic and evaluation • Wed 10/29 - section review (everything from 9/30-10/28) • Thu 10/30 - Exam 2 Lecture 10: Sexual life cycle Advantage of sexual reproduction? Alternation of generations in land plants. Haploid generation becomes heterotrophic and smaller. Diploid generation becomes autotrophic and larger. Less dependency on environmental water for fertilization
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BSC 2011 Kitajima week 4 2 Meiosis and fertilization • Meiosis refers to the special cell division in which chromosome number is halved from two sets (2n) to one set (1n). A resulting haploid cell is a spore . • A spore can conduct mitosis to become a multicellular gametophyte that can produce gametes by mitosis. • Fertilization is the process of uniting two gametes to create a zygote , a diploid cell (2n). • A zygote conducts mitosis to become a multicellular embryo, a sporophyte (2n). Sexual cycle = alternation of generations between haploid and diploid generations Diploid multicellular organism Key MEIOSIS FERTILIZATION MEIOSIS FERTILIZATION MEIOSIS FERTILIZATION n n n n n n n n n n n n n 2n 2n 2n 2n 2n Zygote Gametes Haploid multicellular organism (gametophyte) Haploid multicellular organism Haploid Diploid Mitosis Mitosis Spores Gametes Mitosis Mitosis Gametes Mitosis Zygote Zygote Mitosis (a) Animals Diploid multicellular organism (sporophyte) (b) Plants and some algae (c) Most fungi and some protists Fig. 13.6
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BSC 2011 Kitajima week 4 3 Fig. 29.5 (pp. 576-7): Alternation of generations and multicellular embryo nursed by gametophyte Haploid multicellular organism ( gametophyte ) Mitosis Mitosis Gametes Zygote Diploid multicellular organism ( sporophyte ) MEIOSIS FERTILIZATION 2 n 2 n n n n n n Spores Mitosis Liverwort gametophyte Archigonium with egg embryo Placental tissue around embryo 10 ± m fertilization zygote Mature sporophytes Young sporophytes Male gametophyte Raindrop Sperm Key Haploid ( n ) Diploid (2 n ) Antheridia Female gametophyte Egg Arclegonia FERTILIZATION Zygote Archegonium (haploid tissue) Embryo Female gametophytes sporangium Spores Protonemata “Bud” MEIOSIS Mature sporophytes Bryophytes: 1) photosynthetic and dominant gametophyte, 2) non-photosynthetic sporophyte nursed by gametophyte, 3) dependency on environmental water for sperm to swim to egg Fig. 29.8
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BSC 2011 Kitajima week 4 4 Ferns: 1) photosynthetic tiny gametophytes, 3) dependence on water for sperm to swim to egg Key Diploid (2
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This note was uploaded on 03/30/2010 for the course BSC BSC2011 taught by Professor Evans during the Spring '10 term at École Normale Supérieure.

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Kitajima_week4_HO2pp1 - BSC 2011 Kitajima week 4 Plan for...

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