BIOLOGY 225 ANIMAL DEVELOPMENT FINAL EXAM REVIEW Complete And Verified Study material) (16pages) LEARNEXAMS

● Animal Development

â—‹ Fertilization

â–  The function of the cortical granules in relation to the vitelline envelope and plasma

membrane

â—‹ Preventing polyspermy

â–  Acrosomal enzymes eat away at the membrane

â–  FAST block: species receptors change the membrane electrical potential by binding to

the bindin proteins on the acrosome...

● Na+ released into the cell making it positively charged

■ Fuse egg and sperm together → Ca+ wave to initiate slow bock

â–  SLOW block: cortical granules fuse with membrane, goes back to negatively charged,

enzymes break connection between membrane and vitelline envelope, envelope

hardens & no bindin proteins for other sperm

■ Egg and sperm nuclei fuse → diploid zygote

â—‹ Cleavage: embryo divides repeatedly into a small cluster of cells forming blastomeres (blastula)

â–  Patterns of Yolk Distribution

● Holoblastic → whole embryo is dividing

○ Isolecithal → equal yolk distribution, most easily cleaved

■ Radial → new cells directly on top of each other forming new

layers

● Regulative development - new organism

■ Spiral → new cells form in furrows that are packed tightly

● Mosaic development - NO new organism

○ Mesolecithal → moderate distribution of yolk

â–  Radial

● Meroblastic → part of the egg yolk remains undivided cluster of cells divide on

top of the yolk

○ Telolecithal → yolk concentrated at vegeta pole

○ Centrolecithal → large centrally located mass of yolk, most likely complete

cleavage

â—‹ Blastulation: cleavage of the cytoplasm

â—‹ Gastrulation: formation of germ layers & coelom by invagination

â–  Germ Layers (outer to inner)