Section 1
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blastopore
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Last updated
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Date created
Mar 1, 2020
Cards (56)
Section 1
(50 cards)
blastopore
opening into second cavity
fertilization
gamete nuclei fuse; for sea urchins sperm penetrates jelly, then contacts vitelline envelope then proteins on the acrosomal process bind species-specific sperm receptors on the vitelline envelope
different types of cells express different sets of genes
how do cells become different?
amniotic egg
four membranes, provides a complete life-support system for the embryo; evolution of the shelled ___ made internal fertilization a requirement
triploblastic animals
everybody but cnidarians; have 3 germ layers; allows for formation of a coelom and organs
induction
extrinisic/positionial information is received from the cell's surroundings; ex a cell might get chemical signals from a neighbor, instructing it to become a particular kind of photoreceptor; fate of cell depends on its interactions with neighboring cells
amniotes
reptiles, birds, mammals; embryos develop within the amnion sac; amniotic egg has four membranes
embryonic period
period from 2-8 weeks; all major organs and body shape form; period that embryo is most sensitive to disturbances that might cause malformation
polyspermy
the entry of more than one sperm to one egg; deleterious to normal development
placental mammals
represents 94% of mammals; evolution of the placenta for embryo nourishment required reconstruction of extraembryonic membranes; had modification of oviduct form uterus
mesoderm
forms between the endoderm and the ectoderm; produces layers of muscles and internal body parts
triploblastic
three germ layers
yolk sac
pre-dates amniotes by millions of years and found in all fish embryos; stores yolk to sustain embryo
blastoderm
single sheet of cells
coelom
body cavity lined with mesoderm; can act as a hydrostatic skeleton, resisting external pressure; allows internal organs to move and grow; acts as protective cushion for their internal organs
chorion
lies beneath the eggshell, enclosing embryo and other membranes; as embryo grows, the need for oxygen increases; allantois and ____ fuse to form a respiratory surface, the chorioallantoic membrane
cytoplasmic specification and induction
_____ determine which genes get expressed in each cell which allows for specialized cell function
axes
to function correctly, that body needs well-defined ____ such as left and right, head and tail
diploblastic animals
cnidarians; have two germ layers; no coelom or organs
cleavage
a sequence of mitotic divisions; zygote is multicellular but does not produce uniform cells; influenced by arrangement of cytoplasm and yolk in zygote
gut cavity
gastrointestinal tract
endoderm
inner layer
slow block
secondary reaction after fast block; cortical granules release contents between the membrane and vitelline envelope; creates an osmotic gradient water rushes into space, elevates envelope, lifts away all other sperm except the one that is fused with plasma membrane
telolecithal eggs
much yolk concentrated at vegetal pole; cleavages is meroblastic/ does not cut through the heavy yolk; found in birds, reptiles, most fishes and a few amphibians
fast block
electrical potential change rapidly spreads across the membrane to prevent the entry of any other sperm; egg becomes positively charged which repels sperm
gastrocoel
gut cavity
amnion sac
fluid-filled sac that encloses the embryo; provides an aqueous environment in which the embryo floats; serves as protection from mechanical shock
cytoplasmic specification
intrinsic/lineage information is inherited from the mother cell, via cell division; ex a cell might inherit molecules that tell it that it belongs to the neural cell-producing lineage of the body
blind gut
incomplete; when the embryonic gut opens only into the blastopore; cnidarians have to digest their food completely or must egest the undigested parts back up the mouth
fluid-filled coelom
body space
isolecithal eggs
very little yolk distributed evenly in cytoplasm; cleavage is holoblastic/complete/ cleavage furrow extends completely through the egg; found in echinoderms, tunicates, cephalochordates, mollusks, and mammals
dorsal neural tube, notochord, pharyngeal gill pouches and aortic arches; ventral heart; postanal tail
ancestral traits of vertebrates
protosomes
blastopore becomes mouth
ectoderm
Outer layer of skin
germinal period
first two weeks; embryo is still dividing and resistant to outside influences
gastrulation
converts the blastula into a 2 to 3 layer embryo; involves an invagination of one side of blastula; gastrocoel, blastopore, ectoderm and endoderm
allantois
storage of metabolic wastes during development; respiratory surface for exchange of oxygen and carbon dioxide
organs
need to be positioned in the right spots along the axes and connected up with one another in the right ways
animal pole
the region containing mostly cytoplasm
blastocoel
fluid-filled cavity inside of blastula
trophoblast
pre-placental cells proliferate rapidly after coming in contact with uterine endometrium; produce enzyme that break down epithelium of the endometrium; allow blastocyst to implant
Centrolecithal eggs
much yolk concentrated in the center; cleavage is meroblastic/ does not cut through yolk at all; superficial cleavage restricts cleavage to the cytoplasmic rim of the egg; occurs in arthropods such as insects
deuterosomes
blastopore becomes anus
vegetal pole
formed by the presence of yolk at only one end
Mesolecithal eggs
moderate amount of yolk concentrated in the vegetal pole; cleavage is holoblastic; occurs in amphibians
blastula
hollow ball of cells; post-cleavage embryo
animal-vegetal axis
establishes polarity in the embryo
complete gut
most animals have a complete pathway from mouth to anus, protostomes and deterostomes
diploblastic
2 germ layers
gamete formation, fertilization, cleavage, gastrulation, organogenesis, growth
sequential and hierarchical progression of development
Section 2
(6 cards)