BIOL303 Study Guide - Final Guide: Melanocyte, Neural Crest, Limb Bud
13 Dec 2016
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Biol 303 final exam prep: sea urchin fertilization and the block to polyspermy. Chemoattraction: directed movement of sperm cells in response to a chemical gradient of chemoattractant peptides from the female reproductive tract. Acrosomal reaction: sperm has receptors for sulphated proteins on the egg jelly coat, which cause the sperm to release its contents from the acrosome. Acrosomal process displays bindin proteins that bind to egg vitelline envelope. Sperm and egg membranes fuse, sperm enters the oocyte. Sperm entry triggers waves of calcium to be released in the egg, which triggers the cortical granule reaction. Fast block to polyspermy = rapid in ux of sodium ions, depolarizes cell, which prevents bindin from working. Slow block to polyspermy = cortical granule reaction: Cortical granules fuse with egg membrane, releasing acrosomal contents. causes the vitelline envelope to from a fertilization membrane, prevents sprm from entering the egg. Gurken: mrna is localized to the anterior dorsal position, where it is translated.
