Mini Quiz, pt2 Ch4,5 Flashcards
what is the signal and receptor b/w delta & notch?
delta = signal
notch = receptor
what are the three steps in differentiation of cells?
- competence
- induction
- commitment (specification, determination)
- differentiation
what is specification and what are the three types?
receiving signal, remained induced in neutral environment (no signals from anyone)
- autonomous, conditional, syncytial
what is autonomous specification?
self directed
- knows what to do when separated from its neighbors
- dependent on cytoplasmic determinants
what is conditional specification?
regulative
- dependent on it’s neighbors if it has them and lets them do some of the work
- can still differentiate by itself when separated, but deviates the work when it can
- dependent on morphogens & induction
what is syncytial specification?
- single cell with many nuclei
- not one cell talking to another
- dependent on concentration gradients
what is bicoid?
gene on anterior end of fruit fly
- head development
what is caudal?
gene that works with nanos on the posterior end
what is determination?
altered TFs (1 of the 4 maintenance processes)
- starts to actively do the signal
- remains induced even in a conflicting environment (many new signals)
what are morphogens?
molecules made in one compartment that create a diffusion gradient between the other morphogens
- in-class demonstration of red & blue dye
- THRESHOLD GRADIENT
what is the difference between a spermatid and sperm?
spermatid
- no viable for fertilization
- no tail
sperm
-tail
- went through spermiogenesis
what things are in the sperm head?
acrosomal vesicle
cell membrane
nucleus
what things are in the midpiece of sperm?
centriole
mitochondria
what things are in the endpiece?
tail
function of the acrosomal vesicle
bag of enzymes that sperm uses to pierce through the oocyte jelly coat (zona pellucida)
function of the centriole
organize the chromosomes and axoneme (microtubules down the tail)
when do sea urchins complete oocyte meiosis?
before fertilization
why aren’t sea urchins good to study?
they don’t survive when trying to reproduce
- unable to follow generations
why do we study sea urchin early embryo development?
finish meiosis
laid so they aren’t in the fallopian tube (external fertilization)
transparent egg and embryo
gametes huge in numbers
easy to see fertilization under lab conditions
what teathers the plasma membrane of a sea urchin oocyte?
vitelline envelope
what is the cortical granule of a sea urchin?
underneath the plasma MB and contains components that react to the sperm when the sperm hits
- mucopolysaccharides, enzymes (cut tethers, new MB)
what is the cumulus?
in mammalian eggs
- contains support / nurse / granulosa / follicle cells
- becomes the corpus lutem (hormones)
what are three problems with external fertilization?
diluted in entire ocean (species not close to eachother)
fertilize wrong species
multiple fertilization (many heads contact egg)
what are the three solutions to the three problems with external fertilization?
diluted in ocean
- sperm attractant, synchronized
wrong species
- bindin binding vitelline envelope
multiple fertilization
- fast & slow blocks
what is the process of sea urchin fertilization?
- egg releases sperm attractant peptide to cause sperm to bend toward egg (conc. gradient)
- sperm contacts jelly layer
- actin extends and pushes on acrosome
- acrosome bursts & releases digestive enzymes to eat jelly coat
- digestion of jelly layer exposes bindin protein (on sperm)
- acts like a ligand - bindin binds vitelline envelope
- requires a species-species recognition to bind - fusion of acrosomal MB and egg MB (creates tunnel)
- fast block
- opens ion channels (Na+ IN, Cl- OUT) - slow block
- cortical granules burst and release enzymes
* proteases cut vitelline ties
* polysaccharides
* peroxidases fix things
* hyalin builds the fertilization envelope to eject extra sperm
what are the early responses of sea urchin fertilization?
- sperm-egg binding
- fast block
- Ca2+ increase
- cortical granule exocytosis (due to Ca2+)
- slow block
what are 1 min late responses?
energy & pH
- activation of kinases, NADPH, O2
- sperm entry
- acid efflux (pH increases, more basic)
what are 10 min late responses?
migration & protein synthesis
- sperm DNA decondenses
- sperm nucleus migration ot egg center
- egg nucleus migrates towards sperm nucleus
- activation of protein synthesis, AA transport
what are 20 min late responses?
- initiation of DNA synthesis
- mitosis
- first cleavage
describe early cleavage
zygote -> blastula
- goes straight from anaphase immediately to S phase
- no G0, G1, or G2
what drives mitosis in early cleavage? describe the process
Cdc2 / cyclin B
- allows the DNA to double
- made during S phase, degraded after M phase
-active during M phase, inactive during S phase - ON/OFF switch
- activates MPF (mitosis promoting factor)
- drives the shift b/w M & S phase
- does this about 10 times
describe late cleavage
blastula -> gametogenesis
- full cell cycle ( G1, S, G2, M)
- cells start to change and differentiate
what is the MBT? (mid-blastula transition)
when the cell goes from early cleavage to late cleavage & gene expression
what is holoblastic cleavage?
COMPLETE
entire cell divides, including the yolk
what are the three types of holoblastic cleavage?
radial
rotational
displaced radial
what is radial cleavage?
first two divisions
- rotate 90* around center
what is rotational cleavage?
mammals
- cut from the side at an angle
- uneven cuts
what is displaced radial cleavage?
yolk parts divide slower
- still divide, just slower
what is meroblastic cleavage?
INCOMPLETE
only embryo/cells divides, not the yolk
what are the two types of meroblastic cleavage?
discoidal
centrolectithal
what is discoidal cleavage?
fish, reptiles, birds
- big yolk and cells divide while laying ontop
what is centrolectithal cleavage?
insects
- multiple nuclei in one cell (syncitium specification)
- no cytokinesis
what are the five types of movements in gastrulation?
- invagination
- involution
- ingression
- delamination
- epiboly
what is invagination?
cells push toward middle and create a pore
what is involution?
cells move inward and create a new lining of cells
- cells move along the layer that produced them
what is ingression?
cells leave the sheet like state and individual cells migrate inward by themselves
what is delamination?
makes the epithelial thicker
- remain same cell type and property
what is epiboly?
cause outer cells to stretch further to cover the entire embryo
- ex: rolling a ball of dough to make pizza crust
what are the three axis?
anteroposterior (A/P axis)
dorsoventral (D/V axis)
proximodistal (P/D axis)
what are micromeres and why are they important in development?
causes cells to differentiate and form axis
- form the mesoderm
- found on the vegital pole
what is the order of movement in sea urchin gastrulation?
- ingression
- invagination
- archenteron
what is archenteron movement?
invagination cells get pushed into the middle to fill the blastocoel
- turn into the primitive gut
what happened when they only let the animal pole develop?
only made the ectoderm
- no induction or migration
- only does autonomous specification
what happened when they only let the animal pole and micromeres develop?
the micromeres induced the animal pole to form a mesoderm
what happened when they added micromeres to the animal pole in addition to the micromeres on the vegital pole?
they did invagination on both poles, created two pores
how do micromeres relate to the Wnt signaling pathway?
they contain disheveled which protects beta-catenin from proteases
- there for allows for target genes to be activated
- thus creates the mesoderm
what are regulatory circuits?
turning one gene on might affect everything else it turns on
describes the double negative gate regulatory circuit
beta-catenin inactivates gene B
-gene B when active, inhibits delta
- therefore when beta-catenin inactivates gene B, it indirectly activates delta
