BIOL 225 Study Guide - Quiz Guide: Membrane Potential, Yolk, Polyspermy
28 Dec 2019
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Fertilization: union of male & female gametes form a zygote. External fertilization release gametes into the h2o. Preventing polyspermy using fast & slow block. Fast block: species receptors change the membrane electrical potential by binding proteins on acrosome of sperm (2 seconds) Cortical granules discharge hypertonic fluid with enzymes into space between the egg & membrane into the vitelline envelope. Slow block: vitelline envelope hardens & membrane becomes fertilized (60 seconds) Egg & sperm nuclei fuse and form a zygote create a ploidy for the cell. Cleavage: nucleus & cytoplasm divide to form new cells (sa) Embryo divides repeatedly into a small cluster of cells forming blastomeres, creating a blastula. Isolecithal equal yolk distribution, most easily cleaved. Radial new cells directly on top of each other forming layers. Regulative development - whole new organism can form. Spiral new cells form in furrows that are packed tightly. Mosaic development - new organism can not be formed.
