Ch.8 - Principles of Development Flashcards
what is spermatogenesis/oogenesis known as?
gamete formation
what was the early fertilization concept (that was wrong)?
preformation
what was the early fertilization concept (that was correct)?
epigenesis
what is epigenesis?
fertilized egg contains raw materials only, that assemble
what is preformation?
miniature embryo in gamete(s) “unfolds”
what are the purposes of fertilization?
1) genetic diversity
2) restore diploidy
3) activate egg
What is the first step in fertilization?
jelly layer penetrated by sperm
what is the second step in fertilization?
fusion with vitelline envelope if egg recognition and sperm receptor proteins match
what draws the sperm head in?
fertilization cone
what is “fast block”?
electrical potential change to vitelline membrane -> blocks other sperm’s fusion
what does the cortical reaction do?
lifts vitelline envelope away
what is the “slow block”?
vitelline envelope hardens = fertilization membrane
when does the removal of inhibitors to egg metabolism occur?
after male and female pronuclei fuse
how are blastomeres made?
eggs cleave
what is isolecithal?
sparse, evenly distributed yolk
what are examples of isolecithal?
mammals, starfish, insects
what is mesolecithal?
moderate amount of yolk at one end
what is an example of mesolecithal?
amphibians
what is telolecithal?
mostly dense yolk; only a disc of cytoplasm on surface divides
what are examples of telolecithal?
birds, reptiles, fish
what is holoblastic cleavage?
whole egg cleaved (yolk slows but does not prevent it)
what has holoblastic cleavage?
isolecithal + mesolecithal
what is meroblastic?
only cytoplasm cleaved (yolk too dense to cleave)
what has meroblastic cleavage?
telolecithal
what is indirect development life cycle?
egg – larva – pupa – adult
what development has metamorphosis?
indirect development
what is the direct development life cycle?
egg – embryo – adult
what is blastula?
hollow ball of cells
what is blastocoel?
blastula’s cavity
what is gastrula?
invagination - blastula indented
what is archenteron?
primitive gut
what is blastopore?
gut’s opening
what is a protostome?
blastopore forms mouth first
what is a deuterostome?
blastopore forms anus first
what is induction?
cells in particular regions of developing embryo determine the developmental response of neighboring cells
what is primary organizer?
region of dorsal lip of gastrula’s blastopore
what is primary induction?
event leading to complete embryo
what is secondary induction?
one tissue induced to differentiate induces another tissue
what is homeotic gene?
specify the identity of specific body segments
what is homeotic mutation?
cause development of wrong structures in a given region
what is amniote?
share an amniotic membrane
what are examples of anamionte?
fish and amphibians
what is amnion?
fluid filled; prevents drying; a shock absorber
what is yolk sac?
provides nourishment
what is allantois?
stores wastes, with chorion, exchanges gases
what does chorion do?
with allantois exchanges gases
what phyla are protostomes?
arthropoda, molluscs, worms
what phyla are deuterostomes?
chordates, echinodermata
what forms external epithelium and nervous system?
ectoderm
what forms muscle tissue, bone, cartilage, repro system, circulatory system, body cavity lining (peritoneum)?
mesoderm
what forms lining of digestive system?
endoderm
what animals are amniote?
reptiles, birds, mammals
