lecture 15 (10-)

lecture 15 (10-) - Plant Reproduction Life Cycle of...

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Plant Reproduction – Life Cycle of Flowering Plants I. Key Features A. Alternation of Generations 1. Sporophyte generation is dominant (2n) 2. Gametophyte is dependent on the sporophyte for nutrition a. Reduced to only a few cells – very small B. Heterosporous 1. Different spores are being produced a. Microspores - male b. Megaspores – female C. Sexual Reproduction 1. Occurs in the flowers D. Double Fertilization II. Life Cycle A. Female Gametophyte 1. Ovary contains one or more ovules 2. Each ovule is a megasporangium a. Contains megasporocyte (2n) b. Megasporocyte undergoes meiosis and produces 4 haploid megaspores c. Three megaspores disintegrate d. One functional megaspore undergoes 3 mitotic divisions of the nucleus 8 haploid nuclei 3. Develops into mature female gametophyte, also known as embryo sac a. Embryo sac is comprised of 7 cells with 8 haploid nuclei b. Six of the cells contain a single nucleus in each c. One of these cells is the egg cell (one nucleus) d. Three of the cells are the antipodals (one nucleus), which disintegrate e. Remaining two cells are synergids (one nucleus), which disintegrate and when they do, they release some chemicals which are essential in growth of pollen tube f. Central cell contains two nuclei (polar nuclei) g. Egg and central cell are directly involved in fertilization B. Male Gametophyte Figure 37-3 1. Anther contains microsporangium (pollen sacs) a. Microsporangium has many microsporocytes (2n) b. Microsporocytes undergo meiosis and produce 4 haploid microspores c. Microspores burst out of microsporocyte and the microspores are released d. Each microspore develops into an immature male gametophyte (pollen grain) e. Pollen cell has 2 cells tube cell and generative cell f. Anther splits open and the pollen sheds C. Pollination 1. Transfer of pollen grains from the anther to the stigma 2. Self-pollination takes place a. Can occur within the same flower
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This note was uploaded on 11/30/2011 for the course BIO 119:101 taught by Professor Martin during the Fall '08 term at Rutgers.

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lecture 15 (10-) - Plant Reproduction Life Cycle of...

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