Animal Development

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  1. As recently as the 18th century, the prevailing theory was called
  2. performation
    is the idea that the egg or sperm contains a miniature infant, or “homunculus,” which becomes larger during development
  3. development is determined by
    the zygote’s genome and molecules in the egg called cytoplasmic determinants
  4. cell differentiation
    is the specialization of cells in structure and function
  5. morphogenesis
    the process by which an animal takes shape
  6. model organisms
    • species that are representative of a larger group and easily studied, for example, Drosophila, Mus musculus and Caenorhabditis elegans
    • Classic embryological studies have focused on the sea urchin, frog, chick, and the nematode C. elegans
  7. Important events regulating development occur during fertilization and the three stages that build the animal’s body, what are the 3 steps?
    • cleavage
    • gastrulation
    • organogenesis
  8. cleavage
    cell division creates a hollow ball of cells called a blastula
  9. gastrulation
    cells are rearranged into a three-layered gastrula
  10. organogenesis
    the three layers interact and move to give rise to organs
  11. Fertilization brings the haploid nuclei of sperm and egg together, forming a what?
    diploid zygote
  12. The sperm’s contact with the egg’s surface initiates metabolic reactions in the egg that trigger the onset of what?
    embryonic development
  13. acrosomal reaction
    triggered when the sperm meets the egg
  14. acrosome
    at the tip of the sperm releases hydrolytic enzymes that digest material surrounding the egg
  15. Image Upload
    sea urchin fertilization
  16. polyspermy
    • when more than one sperm gets in the egg
    • Gamete contact and/or fusion depolarizes the egg cell membrane and sets up a fast block to polyspermy
    • Fast block does not exist in mammals
  17. Fusion of egg and sperm also initiates the what?
  18. the reaction induces a rise in Ca2+ that stimulates what to release their contents outside of the egg
    cortical granules
  19. first two steps of the cortical reaction form a fertilization envelope functions as a what?
    • slow block to polyspermy
    • In mammalian fertilization, the cortical reaction modifies the zona pellucida, the extracellular matrix of the egg
  20. Image Upload
    mammal fertilization
  21. The sharp rise in Ca2+ in the egg’s cytosol increases the rates of cellular respiration and protein synthesis by the
    egg cell
  22. With these rapid changes in metabolism, the egg is said to be what
  23. The sperm nucleus merges with the egg nucleus and what happens?
    cell division begins
  24. Image Upload
  25. gastrulation
    rearranges the cells of a blastula into a three-layered embryo, called a gastrula, which has a primitive gut
  26. The three layers produced by gastrulation are called embryonic germ layers which are?
    • The ectoderm forms the outer layer
    • The endoderm lines the digestive tract
    • The mesoderm partly fills the space between the endoderm and ectoderm
  27. Image Upload
  28. amniotes
    Embryos of birds, other reptiles, and mammals develop in a fluid-filled sac in a shell or the uterus
  29. During amniote development, four extraembryonic membranes form around the embryo which are?
    • The chorion functions in gas exchange
    • The amnion encloses the amniotic fluid
    • The yolk sac encloses the yolk
    • The allantois disposes of waste products and contributes to gas exchange
  30. Image Upload
    extraembryonic membrane
Card Set:
Animal Development
2013-05-08 16:30:05
Life 103

Test 4
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