[BIO 1306] Ch42_Lecture

[BIO 1306] Ch42_Lecture - 42 Animal Reproduction 42 Animal...

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42 Animal Reproduction
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42 Animal Reproduction 42.1 How Do Animals Reproduce without Sex? 42.2 How Do Animals Reproduce Sexually? 42.3 How Do the Human Male and Female Reproductive Systems Work? 42.4 How Can Fertility Be Controlled and Sexual Health Maintained?
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42.1 How Do Animals Reproduce Without Sex? Asexual reproduction requires no mating but does not result in genetic diversity. Asexually reproducing species are mostly invertebrates, sessile, and live in constant environments. Three types of asexual reproduction are budding , regeneration , and parthenogenesis .
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42.1 How Do Animals Reproduce without Sex? Budding produces new individuals that form from the bodies of older animals. A bud grows by mitotic cell division and cells differentiate before the bud breaks away. The bud is genetically identical to the parent.
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Figure 42.1 Asexual Reproduction in Animals (A)
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42.1 How Do Animals Reproduce without Sex? Regeneration can replace damaged tissue or may form a complete individual. Example: Echinoderms
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Figure 42.1 Asexual Reproduction in Animals (B)
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42.1 How Do Animals Reproduce without Sex? Parthenogenesis is the development of offspring from unfertilized eggs. Parthenogenesis may determine the sex of the offspring. In some species, females can act as males depending on cyclic states of estrogen and progesterone.
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Figure 42.2 Sexual Behavior May Be Required for Asexual Reproduction (Part 1)
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Figure 42.2 Sexual Behavior May Be Required for Asexual Reproduction (Part 2)
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42.2 How Do Animals Reproduce Sexually? In sexual reproduction two haploid cells form a diploid individual. Gametogenesis produces haploid gametes through meiotic cell division. Meiosis allows genetic diversity through crossing over , between homologous chromosomes, and independent assortment .
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42.2 How Do Animals Reproduce Sexually? Three fundamental steps of sexual reproduction: Gametogenesis: making gametes Mating: getting gametes together Fertilization: fusing gametes
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42.2 How Do Animals Reproduce Sexually? Gametogenesis occurs in the gonads. In males the gonads are the testes and the gametes are small, motile sperm . In females the gonads are the ovaries and the gametes are nonmotile ova , or eggs.
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42.2 How Do Animals Reproduce Sexually? Gametes are produced from germ cells , which occur early in development and are distinct from the rest of the body. All other embryonic cells are called somatic cells . Germ cells migrate to the gonads when they begin to form.
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42.2 How Do Animals Reproduce Sexually? Germ cells undergo mitosis and produce spermatogonia in males and oogonia in females. Mitosis continues and produces primary spermatocytes and primary oocytes , both diploid. Meiosis produces haploid cells that mature into sperm and ova.
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42.2 How Do Animals Reproduce Sexually? Spermatogenesis
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This note was uploaded on 04/08/2008 for the course BIO 1306 taught by Professor Adair,tamarah during the Spring '08 term at Baylor.

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[BIO 1306] Ch42_Lecture - 42 Animal Reproduction 42 Animal...

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