Kitajima_week4_HO3pp1 - BSC 2011 Kitajima week 4 Plan for...

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BSC 2011 Kitajima week 4 1 58 Plan for Week 4 & 5 to finish up Chapters 38 & 39 • Tue 10/21 - alternation of generations (pp. 242, 576- 7,580-1, 584-5, 771-772) & chapters 35-37 review • 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 biotic stresses (pp. 808-815); integration & course evaluation • Wed 10/29 - section review (everything from 9/30-10/28) • Thu 10/30 - Exam 2 59 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 60 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).
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BSC 2011 Kitajima week 4 2 61 Sexual cycle = alternation of generations between haploid and diploid generations Diploid multicel ular 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 multicel ular 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 62 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 63 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 3 64 Ferns: 1) photosynthetic tiny gametophytes, 2) photosynthetic & large sporophytes, 3) dependence on water for sperm to swim to egg Key Diploid (2 n ) Haploid ( n ) Fig. 29.12 65 Seed plants: 1) gametophyte reduced to embryo sac and mature pollens, 2) dominant sporophytes, 3) no need for rain drop for fertilization Anther at tip of stamen
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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_HO3pp1 - BSC 2011 Kitajima week 4 Plan for...

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