Human Reproduction

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Human Reproduction
2013-01-16 15:09:21
BIO 220

Lecture Powerpoints
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  1. What is the function of the reproductive system?
    propagation of the species, so that generations after generations can be in existence
  2. Types of reproduction:
    Which occur in animals?
    Which one is used?
    • asexual and sexual
    • both
    • both, one or none
  3. Asexual reproduction: __
    • propagation of a new offspring by mitosis; one parent (monotonous reproduction
    • Result: produces a genetically identical copy of itself, a clone; no genetic variation
  4. What are the kinds of asexual reproduction?
    • budding
    • fission
    • gemmules
    • fragmentation
    • parthenogenesis
  5. Explain budding
    • budding: outgrowths of existing individuals; a group of cells grow on the body and, through mitosis, grows to become a new individual, which then detaches
    • ex: invertebrates
  6. Explain fission
    separation individuals of approximately the same size.
  7. Explain gemmules.
    specialized diploid cells are partitioned (set aside) somewhere in the parent--> released into the environment--> divide mitotically to form a new individual
  8. Explain fragmentation.
    • breaking into pieces, where each piece regenerates its missing part by regeneration
    • Example: earthworm
  9. Explain parthenogenesis
    • a new haploid individual forms from an unfertilized egg
    • Individuals are sterile; some remain haploid; others turn diploid
    • Example: bees [worker]
  10. Advantages of asexual reproduction.
    • not finding mate; if species is scarce, they don't worry
    • more offspring at a faster rate
    • if the gene pool is favorable, it passes on, assuring persistence
  11. Disadvantages of asexual reproduction.
    • If there is a bad gene, it is transferred
    • lack of diversity
    • unfavorable genes perpetuate (deleterious)
  12. What is sexual reproduction?
    • two parents each produce haploid gametes, fuse in fertilization, and form a diploid zygote
    • - creation of an offspring by fusion of a male gamete (sperm) and female gamete (egg) to form a zygote
  13. Gametes form by __--> fertilization--> zygote--> grows by __.
    • meiosis
    • mitosis
  14. Advantages of sexual reproducion?
    • genetic variation via recombination and independent assortment
    • - every offspring can be genetically differetn from every other offspring
    • - recombination does a good job hiding deleterious genes (recessive genes)
    • Changing environments are accommodated through adaptations
  15. Disadvantages of sexual reproduction.
    • finding a mate
    • takes a longer time
  16. Hermaphrodism
    • individuals contain both male and female gonads and other reproductive structures
    • They reproduce sexually, but do not self-fertilize [eggs can be fertilized by own sperm]
    • Example: earthworm and sea slugs (sea slugs produce own sperm and eggs; in a few weeks, new individuals hatch from fertilized eggs)
  17. Some species undergo __. Explain it.
    • sex reversal
    • female can change into a male and vice versa via environmental cues
  18. What does all fertilization require?
    • critical timing
    • mediated by environmental cues (pheromones and chemical attractants (maybe))
    • courtship and mating behaviors
  19. What are the two types of fertilization in sexual reproduction?
    external and internal
  20. External fertilization.
    • 1) union of gametes outside body:- male and female release gametes into environment; has to be moist environment
    • 2) accompanied by large #s of gametes being spread to ensure some gametes will be successful in finding other gametes: - the further the distance away the male is from the female, the more eggs the female sheds (only females; sperm is always in large #s)
    • 3) Attraction to eggs: - pheromones and chemical attractants
  21. What are phermones and chemical attractants?
    • pheromones: hormones that are released that help lure/ affect behavior of opposite sex
    • chemical attractants: materials released by the outer coats of eggs/ some are highly specias specific/ characteristic of external because internal isn't as important
  22. Why are courtship behavior and mating behaviors important?
    important for proper union
  23. Internal fertilization.
    • 1) The sperm are deposited inside female--> gametes fuse inside body
    • 2) Requires some behavioral interactions- a copulatory organ--> male needs some way to place sperm inside body
  24. What is special about internal fertilization?
    • development can be outside or inside body
    • There are three types of organisms depending on whether development is inside or outside the body.
  25. Internal fertilization and the modes of development.
    • oviparous
    • viviparous
    • ovoviviparous
  26. Explain oviparous.
    • 1) egg-laying animals
    • 2) little/ no development occurs in mom
    • 3) before egg is shed, its covered with protective casing (may be hard shell or leathery)
    • Examples: most fish, amphibians, and reptiles; all birds; most insects; etc.
  27. Explain vivaparous.
    • 1) internal fertilization and internal development where the embryo and the mom are connected by a placenta formed between the mom and baby
    • 2) Mom's blood vessels in close proximity to th ebaby's blood vessels, enabling nourishing of the baby, waste being taken away, etc. by the placenta
    • Examples: all placental mammals, except marsupials.
  28. Explain Ovivivaparous.
    •  1) internal fertilization, but the embryos are carried in body, either the male or female body
    • 2) no interaction between the parent body and embryo
    • 3) embryo grows in self-sufficient manner, not relying on parent for anything but a place during its growth
    • 4) appears as live birth because the casing breaks open and allows release of offspring
    • Examples: marsupials and frogs
  29. Explain reproductive cycles.
    • 1) most animals exhibit reproductive cycles related to changing seasons
    • 2) Reproductive cycles are controlled by hormones and environmental cues.
    • 3) Estrous vs. Menstrual
  30. Explain the estrous reproductive cycle.
    • Occurs in most female placental mammals, except humans.
    • It is often referred to as "heat" where the female is reproductively receptive to the male; corresponds to ovulation cycle in female where she is receptive to intercourse with the male
    • Humans and males are exceptions
  31. Any organism that reproduces sexually must have:
    • gonads (gametes/ sex hormones)
    • accessory structures (ducts/ glands)
    • external genitalia
  32. pair of primary reproductive organs
  33. Accessory structures
    play role in nourishment, transport, protection of fertilized egg and developing embryo
  34. External genitalia
    necessary for union of male and female