Bio 101 Day 15

Bio 101 Day 15 - Reproduction in Flowering Plants...

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Reproduction in Flowering Plants Alternation of Generations -A diploid sporophyte generation (large and nutritionally independent) -A haploid gametophyte generation, located in the flower that is microscopic and nutritionally dependent on the sporophyte generation Environmental Cues -Facilitate the switch between vegetative and reproductive development -Involves activation and inactivation of genes e.g. -Flowering Locus C gene—transcriptional factor that represses flowering Floral Structure 1 Receptacle -Tip of stalk where most of flower parts are born Sepals -Cover and protect flower parts in bud Petals -Attract animal pollinators to flower Stamens -Produce pollen grains Floral Structure Pistil (also known as a carpel) -Female reproductive unit: Stigma—where pollen grains land Style—through which pollen tube grows Ovary contain ovules Each ovule contains
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1 egg 2 polar nuclei Several other nuclei Floral Structure Stamen -Male reproductive unit: Filament—attached to saclike ANTHER (pollen grains form) Each microspore (pollen grain) consists of two cells: Generative cell—forms two non-flagellate sperm cells by mitosis Tube cell—produces a pollen tube to transport the sperm to the ovule Pistil -A simple pistil is also known as a carpel—consists of one stigma, style, ovary and accompanying ovules -A compound pistil—is made up of two or more fused carpels Male and Female Gametophytes (n) FEMALE: (meiosis) Mature Sporophyte (2n) Megasporangium Megasporocyte Four Megaspores (one functional, three disintegrate) Functional Megaspore (n) produces 3 antipodal cells, 2 polar nuclei, 2 synergids, Egg cell (mitosis) MALE: (meiosis) Mature Sporophyte (2n) Microsporangium Microsporocyte Four Microspores Each Microspore Pollen Grain (n) containing Generative cell (forms two sperm cells) and a tube cell (mitosis)
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Pollination -Pollen grains are transported to stigmas by a variety of agents, such as animals and wind -Self-pollination: within same flower or different flower on same individual plant
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This note was uploaded on 04/06/2010 for the course BIO 01-119-10 taught by Professor D'arville during the Fall '09 term at Rutgers.

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Bio 101 Day 15 - Reproduction in Flowering Plants...

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