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Unit 5

Unit 5. Animal Reproduction. Sexual & Asexual Reproduction. Asexual Offspring all have same genes (clones) No variation Sexual Gametes (sperm & egg)  fertilization Mixing of genes  variation. Fertilization. Joining of egg & sperm External Usually aquatic animals Internal

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Unit 5

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  1. Unit 5 Animal Reproduction

  2. Sexual & Asexual Reproduction • Asexual • Offspring all have same genes (clones) • No variation • Sexual • Gametes (sperm & egg)  fertilization • Mixing of genes  variation

  3. Fertilization • Joining of egg & sperm • External • Usually aquatic animals • Internal • Usually land animals

  4. Development • External • Development in eggs • Internal • Placenta • Exchange food & waste • Live birth

  5. Adaptive Advantages? • What is the adaptive value of each type of sexual reproduction • Number of eggs? • Level of parental of care • Habitat?

  6. Reproductive Hormones • Testosterone • From testes • Functions • Sperm production • 2° sexual characteristics • Estrogen • From ovaries • Functions • Egg production • Prepare uterus for fertilized egg • 2° sexual characteristics

  7. Sex Hormone Control in Males Hypothalamus GnRH Pituitary FSH & LH Testes Testosterone Body cells

  8. Male Reproductive System • Testicles • Produces sperm & hormones • Scrotum • Sac that holds testicles outside of body • Epididymis • Where sperm mature • Vas deferens • Tubes for sperm to travel from testes to penis • Prostate, seminal vesicles, Cowper’s (bulbourethal) glands • Nutrient rich fluid to feed & protect sperm • Buffer to counteract acids in vagina

  9. Spermatogenesis Testis Epididymis Germ cell (diploid) Coiled seminiferous tubules 1° spermatocyte (diploid) MEIOSIS I 2° spermatocytes (haploid) MEIOSIS II Vas deferens Spermatids (haploid) Spermatozoa Cross-section of seminiferous tubule

  10. Female Reproductive System • Ovaries • Produces eggs & hormones • Uterus • Nurtures fetus; lining builds up each month • Fallopian tubes • Tubes for eggs to travel from ovaries to uterus • Cervix • Ppening to uterus, dilates 10cm (4 inches) for birthing baby • Vagina • Birth canal for birthing baby

  11. Female Reproductive System

  12. LH Menstrual Cycle FSH Hypothalamus egg development ovulation = egg release GnRH corpus luteum Pituitary FSH & LH estrogen progesterone Ovaries lining of uterus Estrogen Body cells days 0 7 14 21 28

  13. Egg Maturation in Ovary • Corpus luteum • Produces progesterone to maintain uterine lining

  14. Female Hormones • FSH & LH • release from pituitary • stimulates egg development & hormone release • peak release = release of egg (ovulation) • Estrogen • released from ovary cells around developing egg • stimulates growth of lining of uterus • lowered levels = menstruation • Progesterone • released from “corpus luteum” in ovaries • cells that used to take care of developing egg • stimulates blood supply to lining of uterus • lowered levels = menstruation

  15. Oogenesis • What is the advantage of this development system? Meiosis 1 completed during egg maturation ovulation Meiosis 2 completed triggered by fertilization

  16. Fertilization

  17. Fertilization • Joining of sperm & egg • Sperm head enters egg

  18. Cleavage • Repeated mitotic divisions of zygote • 1st step to becoming multicellular • zygote  morula  blastula

  19. Gastrulation • Establish 3 cell layers • Ectoderm • Outer layers • Skin, nails, teeth, nerves • Mesoderm • Blood, bone & muscle • Endoderm • Inner lining • Digestive system

  20. Placenta • Materials exchange across membranes

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