My_Ch46_lecture_rev

My_Ch46_lecture_rev - Chapter 46: Animal Reproduction...

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Chapter 46: Animal Reproduction Purpose: to understand basic reproductive processes in animals, especially humans What you MUST know in Ch 46: Parthenogenesis Hermaphroditism External vs. internal fertilization Female menstrual cycle Role of semen in male Male urethra anatomy (reproductive/excretory) Hormonal control of testes Read Cliff’s. Do not get confused by the amount of detail in Campbell’s—especially re: menstrual cycle hormones. First, the exceptions to sexual reproduction: Parthenogenesis = female independence! Asexual reproduction o Aphids (insects), rotifers, Daphnia (freshwater crustacean) o Bees, wasps, ants (males form from parthenogenesis; females from fertilized eggs) o Some fish, amphibians, lizards Egg development into an adult without fertilization Either results in haploid adults or chromosomes are doubled after meiosis to form diploid adults Hermaphroditism Individual has both male and female reproductive systems Can mate with self or with someone else
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The rest of what you need to know is normal sexual reproduction: External fertilization —occurs outside the body Eggs are shed by the female and fertilized by the male in the external environment Requires moist environment (habitat) Courtship behavior increases probability of successful fertilization (so eggs and sperm will meet at the same time) Fish, amphibians Internal fertilization Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract Requires cooperative behavior, leading to copulation Requires complex reproductive systems (anatomy) that lead sperm to eggs Human Gametogenesis Occurs by meiosis in the: ovary (female), forming eggs (oogenesis) testes (male), forming sperm (spermatogenesis) Oogenesis Begins during embryonic development! Fetal oogonia divide by mitosis to form primary oocytes , which begin meiosis, but stop at prophase I At puberty, 1 primary oocyte during each menstrual cycle continues through the rest of meiosis I, developing in a follicle , which protects and nourishes the developing oocyte In meiosis I, cytoplasm is concentrated in 1 of the daughter cells (unequal cytokinesis), so that at the end of meiosis I:
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o 1 daughter cell is the secondary oocyte , with most of the cytoplasm
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This note was uploaded on 09/29/2011 for the course BIO 020.152 taught by Professor Pearlman during the Fall '08 term at Johns Hopkins.

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My_Ch46_lecture_rev - Chapter 46: Animal Reproduction...

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