Bio Chap 13

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  1. fertilization
    • a haploid sperm fuses with a haploid egg ->hapliod gametes 
    • ->fertilized egg = zygote (diploid)
  2. Repoduction/ Life cycles
    Meiosis -> Gamates haploid -> Fertilization -> Zygote dipliod (human/ animal)

    • 3types :
    • -Haploid multicellular organism  (Plants/algae)
    • -Haploid unicellula/multi organism (fungi/protist/algae)
  3. alternation of generations (Haploid multicellular organism  (Plants/algae)
    • Sporophyte -> gametophyte  (Mitosis)-> sporophyte
    • Plants and some species of algae exhibit a second type of life cycle
    • includes both diploid and haploid stages that are multicellular.
    • sporophyte - multicellular diploid stage
    • gametophyte - multicellular haploid stage
  4. Haploid unicellula/multi organism (fungi/protist/algae)
    Meiosis produces not gametes but haploid cells that then divide by mitosis and give rise to eitherunicellular descendants
  5. homologous pair
    • individual chromosomesthat were inherited from different parents
    • have different versionsof genes, each called an allele at loci
  6. Meiosis I (2n + 2n) -> Meiosis II(4(n) daughter cells gamates)

    reductional division->equational division(sister chromotids seperate to chromosome)
    • Interphase(duplicate homologous chromosome)
    • ->Prophase I (synapsis, crossing over, chiasmata(X shaped) -> Metaphase I (line up, centrsome fiber connect) -> Anaphase I (seperate aparat homologous) -> Telophase I ( nuclear evelope is forming, seperate)
  7. Origins of Genetic Variation Among Offsping
    • -Independent Assortment of Chromosomes
    •     -random orientation of pairs of homologous chromosomes(maternal or paternal) at metaphase I
    •     -possible combinations : 2^n Ex: human= 2^
    • -Crossing Over
    •   -recombinant chromosomes: carry genes (DNA) derived from two different parents, a paternal chromatid is joined to a piece of maternal chromatid
    • -Random Fertilization
    •       -each male and female gamete represents one of about 8.4 million -> 70 trillion zygote

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Bio Chap 13
2012-11-18 23:34:34

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