Biochemistry 3381A Study Guide - Quiz Guide: Zona Pellucida, Acrosome Reaction, Spindle Apparatus
27 May 2020
School
Department
Course
Professor
Document Summary
Binding to the zona pellucida (mammals: the zona pellucida is a glycoprotein matrix that surrounds the egg, the glycoproteins are involved in sperm binding (sed1, zp3) and initiation of the acrosome reaction (zp3, the binding has some species-specificity. The acrosome reaction (mammals: the acrosome reaction is initiated by zp3, acrosomal enzymes (mainly proteases) digest the zona pellucida, thus. Zp3 activates ca2+ influx that stimulates acrosomal exocytosis enabling the sperm to penetrate it the equatorial domain of the sperm membrane binds to microvilli from the egg sperm and egg membrane fuse sperm content is internalized. A problem has to be avoided: polyspermy two sperms entering oocyte: triploid zygote with two mitotic spindles first cleavage results in four blastomeres with random numbers of chromosomes. Disintegrating cells causes death of the embryo a fast block to polyspermy is reached by a shift of the membrane potential of the sea urchin egg. Shortly after fertilization the membrane potential shifts from -70 mv to.
