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Reproductive Biology. Cell Division Somatic cell division (Mitosis) Reproductive cell division (Meiosis) Flowering and Anthesis Megagametogenesis (EMC to Egg Cells) Microgametogenesis (PMC to Pollen Grains) Pollination and Fertilization Pollen germination on stigma
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Reproductive Biology • Cell Division • Somatic cell division (Mitosis) • Reproductive cell division (Meiosis) • Flowering and Anthesis • Megagametogenesis (EMC to Egg Cells) • Microgametogenesis (PMC to Pollen Grains) • Pollination and Fertilization • Pollen germination on stigma • Pollen tube growth through style tissue • Double fertilization
Mitosis • - Somatic Cell Division • Ends up with same number of chromosomes in divided cells • Divided cells are genetically identical to maternal cells 2N ---------► 2N + 2N
Meiosis • Reproductive cell division • Undergoes 2 separate divisions • Forms gametes • Divided cells have a half of the chromosome numbers • Ends up with genetic re-assortment by chromosomal translocation (cross-over) 2N ---►---► N + N + N + N
Chromosome Numbers Terminology x = Number of chromosomes in a genome Genomic chromosome number A set of different chromosomes “Oneness” n=Number of chromosomes in gametes Gametic chromosome number “Halfness” 2n = Number of chromosomes in somatic cells Somatic chromosome number “Wholeness”
Polyploidization • Use of Cholchicine to induce polyploids • Colchicine interferes with spindle fiber function during metaphase of meiosis
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Polyploidy Terminology (continued) • Euploidy Variation between chromosome sets • Aneuploidy Variation within a chromosome set • Autoploidy Multiplication of the complete set of genomes of a species • Alloploidy Polyploid containing genetically different sets of chromosomes derived from 2 or more species
AneuploidyVariation within a chromosome set A diploid plant (2n=2x=14) would contain the following chromosome numbers depending on aneuploidy conditions:
Life Cycle • Alternation of gametophytic (n) and sporophytic (2n) stages in a cycle • Sporophytic (2n) stage is long and gametophytic (n) stage is brief
Pollen Tetrad and Microgametophyte - One tube nucleus - Two sperm nuclei
Megagametophyte 1 egg nucleus 2 polar nuclei 3 antipodal nuclei 2 synergids
Double Fertilization A process of fertilization in which one male gamete (sperm nucleus, n) unites the egg nucleus (n) to form embryo (zygote, 2n) and the other sperm nucleus (n) unites polar nuclei (2n) to form endosperm (3n)
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Inheritance of Flower Colorin Velvet Flower(Salpiglossis sinuata) RR or R- = Red flower color rr = Yellow flower color DD or D- = Solid color pattern dd = Dilute color pattern
P1 P2 x Dilute Red (RRdd) Solid yellow (rrDD) F1 Solid Red (RrDd) F2 Solid red (R-D-) 9 Dilute red (R-dd) 3 Solid yellow (rrD-) 3 Dilute yellow (rrdd) 1
RRDD or R-D- (red, solid) RRdd or R-dd (red, dilute) rrDD or rrD- (yellow, solid) rrdd (yellow, dilute)