chapter50%20-%20development%20_1_

chapter50%20-%20development%20_1_ - Animal Development...

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Animal Development Chapter 50 The development of the form of an animal is a consequence of a balanced combination of several fundamental processes:
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Cell Potency http://en.wikipedia.org/wiki/Cell_potency
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Differential Gene Expression Cell differentiation is normal process by which less specialized cell develops or matures to possess determined (irreversible commitment to specific fate) or distinct form and function (differential gene expression) During cell differentiation, all cells express nuclear equivalence ie all cells have the same gene pool; no genetic change or loss in genetic information
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Morphogenesis Requires cell division and growth, as well as cellular differentiation and pattern formation
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Development 5 stages of development include: 1. Fertilization : 2. Cleavage : 3. Blastulation: 4 . Gastrulation : 5. Organogenesis:
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Fertilization External fertilization e.g. echinoderms, amphibians PM of egg is surrounded by vitelline envelope , plus a glycoprotein jelly coat Internal fertilization e.g. mammals PM of egg surrounded by thick and noncellular zona pellucida, and then a layer of follicular cells corona radiata
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External Fertilization (Echinoderms Fig 50-1) http://biology.kenyon.edu/courses/biol114/Chap13 /Chapter_13B.html Species-specific bindin receptors on egg vitelline envelope only recognize bindin molecules on sperm from same species. "lock and key" mechanism ensures eggs fertilized ONLY by sperm of same species (preventing interspecific fertilization)
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External Prevention of Polyspermy (Echinoderms) Fast block (transient and immediate) causes opening of Na+ channels in egg PM; membrane depolarization prevents additional sperm from fusing to egg PM; normal potential restored within minutes of fusion
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This note was uploaded on 03/08/2011 for the course BIO 119 taught by Professor Transue during the Spring '09 term at Rutgers.

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chapter50%20-%20development%20_1_ - Animal Development...

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