BIOL 225 Study Guide - Final Guide: Membrane Potential, Yolk, Acrosome
28 Dec 2019
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Document Summary
The function of the cortical granules in relation to the vitelline envelope and plasma membrane. Acrosomal enzymes eat away at the membrane. Fast block: species receptors change the membrane electrical potential by binding to the bindin proteins on the acrosome Na+ released into the cell making it positively charged. Fuse egg and sperm together ca+ wave to initiate slow bock. Slow block: cortical granules fuse with membrane, goes back to negatively charged, enzymes break connection between membrane and vitelline envelope, envelope hardens & no bindin proteins for other sperm. Egg and sperm nuclei fuse diploid zygote. Cleavage: embryo divides repeatedly into a small cluster of cells forming blastomeres (blastula) Isolecithal equal yolk distribution, most easily cleaved. Radial new cells directly on top of each other forming new layers. Spiral new cells form in furrows that are packed tightly. Meroblastic part of the egg yolk remains undivided cluster of cells divide on top of the yolk.
