Ch 7 - Fertilization

What are the four main stages of fertilization?
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The egg (or oocyte) has a large mass of cytoplasm storing:ribosomes and nutritive proteins. - Some mRNAs and proteins that will be used as morphogenetic factors are also stored in the egg. - Many eggs also contain protective agents needed for survival in their particular environment.Surrounding the egg cell membrane is an extracellular layer often used in sperm recognition. In most animals this is the: ___________________ In mammals it is the: __________________vitelline envelope zona pellucidaNeither the egg nor the sperm is the "active" or "passive" partner; the sperm is activated by the egg, and the egg is activated by the sperm. Both activations involvecalcium ions and membrane fusionseggs secrete diffusible molecules that attract and activate the sperm. These can be _____________________, providing direction toward the egg of the correct species of sperm.species-specific chemotactic moleculesThe acrosome reaction releases enzymes exocytotically. These proteolytic enzymes do what?digest the egg's protective coating, allowing the sperm to reach and fuse with the egg cell membrane.Polyspermy results whentwo or more sperm fertilize an egg. It is usually lethal, since it results in blastomeres with different numbers and types of chromosomes.T/F: Many species have only one block to polyspermy.False; Many species have two blocks to polyspermy.The fast block is _______________ and causes __________, resulting inimmediate and transient - causes the egg membrane resting potential to rise. - Sperm can no longer fuse with the egg.The slow block is also calledcortical granule reactionThe slow block is _______________, and is mediated by _________ ions. A wave of ______ propagates from the point of sperm entry, causing the cortical granules to fuse with the egg cell membrane.physical and permanent calcium Ca2+The fusion of sperm and egg causes re-initiation of the egg'scell cycle and subsequent mitotic division, and the resumption of DNA and protein synthesis.The ____________ of sperm from the vagina to the egg is regulated by the muscular activity of the uterus, by the binding of sperm in the ___________ of the oviduct, and by directional cues from the oocyte or the cumulus cells surrounding it.translocation isthmusMammalian sperm must be ____________ in the female reproductive tract before they are capable of fertilizing the egg.capacitatedCapacitated mammalian sperm can penetrate the _____________ and bind the _________________cumulus zona pellucida.the acrosome-intact sperm bind to ZP3 on the zona, and ZP3 induces the sperm to undergo :the acrosome reaction on the zona pellucidathe acrosome-reacted sperm, having been induced to undergo the acrosome reaction in the cumulus,bind to ZP2blocks to polyspermy include modification of the zona proteins by the contents of the ___________ so that sperm can no longer bind to the zona.cortical granulesThe rise in intracellular free Ca2+ at fertilization in mammals causes the degradation of _________ and the inactivation of MAP kinase, allowing the _________________ to be completed and the formation of the mature _________________cyclin second meiotic metaphase female pronucleus.T / F: The DNA replication halts while the pronuclei are traveling toward each otherDNA replication takes place as the pronuclei are travelling toward each other. The pronuclear membranes disintegrate as the pronuclei approach each other, and their chromosomes gather around a common metaphase plate.