Unit 2 Exam Flashcards
(76 cards)
1
Q
The fertilization envelope…
A
separates the contents of the nucleus from the cytoplasm and provides the structural framework of the nucleus
2
Q
Cadherins function via direct binding between cadherin molecules on one cell and…
A
Cadherin molecule of another cell
3
Q
Cells tend to form aggregate…
A
- Depend on the type of cadherin it possess
- To reflect their respective positions in the embryo
- To show selective affinity
4
Q
The cell surface tension ….
A
- Dependent on the level of adherin molecule
- Determines the localized position of the cell type
- Highest in the center
5
Q
Which one of the following is not a juxtacrine signaling system?
A
Cell communication that requires direct contact
- FGH, Hedgehog, wnt, TFG-n, Hippo
6
Q
The receptor for Wnt …
A
Wnt binds to Glypican, a HSPG, on a nearby cell when secreted. Glypican transfers Wnt to the Frizzled receptor, causing a secretion of Notum to cleave Wnt’s lipids-signaling molecules that regulate cell-to-cell interactions during embryogenesis. Wnt proteins bind to receptors of the Frizzled and LRP families on the cell surface.
7
Q
Which of the following molecules has a role in sperm chemotaxis in vertebrates?
A
Crisp-1 and calcium
8
Q
Which of the following genes are expressed during amphibian eye induction?
A
- Otx2, Pax6, Sox3
- bmp4 AND fgf8
9
Q
In the absence of a Wnt signal…
A
GSK is active and cytosolic beta-catenin is constantly degraded
10
Q
The hippo pathway plays a role in the inner mass formation…
A
- of organ size
- controls Proliferation
- Involved in apoptosis
- stops mitosis
11
Q
The acrosomal reaction (in animals with internal fertilization) can occurs at the level of ..
A
- Jelly layer
11
Q
Heparan Sulfate proteoglycans are important for
A
- directing diffusion of Fgf8
- Fostering the congregation and secretion of hedgehog molecules as lipoprotein assemblies
- keeps secreted Wnt close to the secreting cellptk signal transduction pathway activated by FGF ligand
- which restricts diffusion and accumulates wnt closer to source of production
11
Q
Lens formation can be induced…
A
- by the optic vesicle signaling or mesenchymal induction
- in the presence of necessary transcription factors
- By Pax6, a paracrine factor required for the surface ectoderm to respond to the inductive signal of the optic vesicle
12
Q
Can the Acrosomal reaction happen before the contact of the zona pelucida
A
Yes
13
Q
During Epithelial-mesenchymal transition
A
The mesenchymal cell, originally part of the epithelial, receives paracrine signals to release itself from the basement membrane by dissociating the apical polarity complexes and adheren junctions binding them to adjacent cells
14
Q
Thanatotropic dysplasia …
A
FgfR3 gain of function mutation causes premature activation of STAT pathway
Block of chondrocyte proliferation
-lethal dwarfism
15
Q
Which of the following molecules are part of the Hedgehog signaling pathway?
A
Smoothened
Patched
PKA
Slimb
Ci (drosophila)
Gli (vertebrates)
Cos2
CK1
GSK3
16
Q
no Hedgehog
A
-Patched-> smoothened-> degredation
-ci is therefore cleaved by PKA cause Ci to be a repressor
17
Q
Wnt1 non-canonical pathway (Planar Cell polarity)
A
- mediates asymmetric cytoskeletal
- it is important in cell migration and there is no participation of LPR5 (instead, RhoaRac)
- binds to Ror and Frizzled at cell surface
- Influences cell behavior AKA Wnt/calcium pathway b-catenin independent causes changes w/in the cytoplasm that influence cell function, shape and behavior
18
Q
At the time of sperm entry, the mammalian egg is
A
- Diploid
- The ovum, is encased in the zona pellucida, which in turn is surrounded by the cells of the cumulus
- A polar body cell, produced during meiosis, is visible within the zona pellucida
19
Q
At the time of sperm entry, the sea urchin egg
A
- haploid
- 3 polar bodies
20
Q
Sea Urchin acrosomal reaction involves
A
- FSP (fucose sulfated polysaccharide) binding to receptor on sperm plasma membrane
- Calcium influx inducing phospholipase enzyme to make IP3
- IP3 releases Ca from acrosome
- Elevated Ca triggers acrosomal releasefushion of the acrosomal vesicle w/ sperm cell mem (exocytosis) the extention of the acrosomal procress enzymes and proteosomes digest a path through the jelly coat adheres to vit envelope testies sperm to egg bindin in acrosome mem
globular -> actin microfilaments
21
Q
The fast block to polyspermy in sea urchins is obtained by
A
- change in resting potential of the egg that is not compatible with fertilization
- Changing membrane potential from -70mV to +20mV
22
Q
In the absence of hedgehog signal
A
Smoothened is degraded Ci (drosophila) and Gli (vertebrates) inhibitors are bound to DNA tethered to mictrotubles cleaved ->Ci acts as a repressor
23
Which one of the following receptor configurations is classic in Canonical Wnt signaling?
-Wnt canonical patway, or beta-catenin pathway, stabilizes b-catenin so that it enters the nucleus and associates with T cell factor, also known as LEF (lymphoid enhacer factor) to activate gene transcription
-Wnt binds to LRP5/6 and frizzled receptor changing LRP5/6's conformation so that it binds Axin and GSK3 inside the cell. Frizzled binds Disheveled which locks the proteins bound to LRP5/6
24
Anoikis...
means apoptosis stimulated by loss of adhesion
25
Signals that lead to the formation of IP3 can ..
-cause a release of calcium from intracellular stores (Ca2+),
-release Ca2+ into the cytoplasm by opening the calcium channels of the endoplasmic reticulum.
slow block
26
Juxtacrine signals induce differential gene expression depending on how far are the cells from the
- cells/cellular receptor
27
Epithelium-mesenchymal induction experiments (frog-salamander transplants) proved that ...
1. it depends on juxtacrine signaling and that the ectoderm is what carries specific genetic information
2. mesenchymal tissue run cross species barriers
3. the ectoderm carries specific genetic programs
4. response of epithelium in species specific
28
The sperm activating protein Rasact ...
-Resact is species specific. Resact also acts as a sperm-activating peptide. Sperm-activating peptides cause dramatic and immediate increases in mitochondrial respiration and sperm motility. Resact is a chemotactic peptide
- isolated from egg jelly of sea urchin diffuses from jelly to sea water and attracts sperm to egg only attracts sperm from a puntulata not other species sperm binds to sperm recasct recptor activates quanylyl cyclase which prouduces more cGAMP that activates ca2+ channel in sperm tail
29
Bindin receptors are
expressed
-on sperm cell acrosomes
-on egg vit envelope
-are species specifc
-thought to be aggregated into comp on vit envelope and hundreds are needed to the sperm to egg
-recognize protein portion of bindin on the acrosome
-activates tyrosine kinase (TK, an Src kinase), which activates PLC.
30
(IMAGE) If the surface tension of (b) is stronger than (a) cells will likely segregate as in:
if there is more surface tension in b, the cells will migrate more centrally towards b
31
Bindin coated beads ..
would lead to agglutination of eggs of the same species of the origin of the bindin sperm
-bind to bindin coating beads species bound to beads w/ same species bindin
32
where are bindin beads located
sperm head
33
In Sea urchin Phospolipase C activation
Wnt binding to the receptor protein (possibly Ryk, alone or in concert with Frizzled) activates a phospholipase (PLC) whose enzyme activities release a compound that in turn releases calcium ions from the smooth endoplasmic reticulum (see Figure 4.34C). The released calcium can activate enzymes, transcription factors, and translation factors.
2. Catalyzes PIP2 to IP3 leads to formation of IP3 which releases ca2+ into egg and initiates egg activation and cortical granule rxn
34
Notch signaling ...
Type of signaling in which the sending cell has a messenger sticking out from its cell membrane and it comes into physical contact with the notch receptor of the other cell
2. can depress repressed genes and can inhibit cell differentiation until deactivated
3. is important for embryogenesis and neurogenesis
35
Which of the following mechanisms plays a role in controlling Fgf8 diffusion?
1. HSPG clustering
2. Dynein LOF
36
Correct hedgehog signaling depends on
the primary sillum
lipid modifications and diffusions in receptor bindin
37
How many polar bodies are generated ...?
three haploid polar bodies
38
How many centrosomes would X sperms ...
2 centrioles = 1 sperm
1 sperm = 2 centrosomes
39
Loss of Wnt4 affects
1. loss of activation which leads to differentiation of the female gonads
2. affects ovary formation makes female gametes male
40
Egg fertilization leads to
-meiosis/zygote
-ca2+ release control granual rxn-> fertilization envelope = slow block
fast block = electrical pot of membrane becoming positive
41
Morphogen gradients...
1. cadherin expression
2. gene expression
42
Gli transcription factors can function as..
repressors or activators for hedgehog pathway when a ligand is bound to absent or patched
43
Lack of functional dynein can lead to....
1. inhibits sperm motility
dynein provides a force for sperm propulsion. without dyenin, the sperm won't move
44
Which of the following Smad proteins are activated in BMP signaling?
smad 1,5
smad 4
smad 2,3 = TGF-b ligand
- serin, theronine
45
Depending on the species the female gamete can be ..
re-fated to become a male gamete
46
During the process of chromosomal crossing over
1. genetic information is shuffled i.e. recombination occurs
2. Cohesion rings encircle sister chromatids and recruit proteins that promote pairing of homologs
47
Primordial germ cells
1. Precursor of germ cells, become oocytes or spermatozoa in the adult
2. are bipotent
3. Are formed in the posterior region of an embryo and migrate to the gonads to induce gonadal development
4. Promote gonad formation
48
The active transcriptional complex downstream BMP signaling is formed by
mobilization of smad proteins
49
Cytonemes are
1. specialized filopodia that transport signaling proteins between cells
2. Cytonemes are filopodia that can extend up to 100mm.
3. capable of establishing a gradient of Hedgehog (Hh) protein over the course of filopodial extension
4. specialized for exchange of signaling proteins between cells
50
Which of the following factors can positively or negatively affect the diffusion of paracrine factors?
cytonemes
HSPG
swim
cilia
protrusions
activin gradient
51
Organisms lacking the molecule Swim
1. does not stabilize wnt so wingless does not disperse
2. reduces the distance/extent of wnt diffusion
3. wnt prematurely binds to target tissues
52
Sonic hedgehog signaling is primarily detected at the level of
1. dorsal epidermis
2. endoplasmic reticulum
3. apicobasal axis of the niche
53
Which of the following molecules is involved in Notch signaling pathway
efferent ligands
54
The Retinoic acid (RA) plays an important role in controlling gamete formation
true
Transcribing Stra8 (transcription factor) to promote DNA synthesis and meiotic division
55
Generation of Zp2 mutants ...
can bind sperm to egg in humans showed that there is a particular region of the mouse Zp2 protein that bound sperm
56
Which of the following molecular mechanism is important in controlling chemotactic attraction of sea
urchins’ sperms?
1. Bindin
2. Resact
57
Notum
-An antagonizer of Wnt
-Removes the lipid off of Wnt secreted when wnt binds to frizzled
-is a hydrolase that assocrates w/ glypolan and eleves off wnts attached lipids in a process of deacylation or delipidation reduces wnt signaling negative feedback
58
Regional specificity experiments of Saunders proved that
Regional specificity of induction in chick development
-Researchers can separate the epithelial and mesenchyme layer and recombine them indifferent ways
-The same epithelium develops cutaneous structures according to the region from which the mesenchyme was taken
-The mesenchyme plays an instructive role calling into play different sets of genes in the responding epithelial cellstype of lutaneous structure is determined by the source of the mesenchyme is responsible for regional specifity
59
Mutations affecting dynein can lead to
1. Both men and women affected by this syndrome are susceptible to
bronchial infections (immotile respiratory cilia) and have a 50% chance of having the heart on
the right side of the body (a condition known as situs inversus, the result of immotile cilia in the
center of the embryo).
2. Kartagener's triad
60
Tyrosine kinase receptors...
can only bind one ligand
-needs HSPG
-dimenize with other RTKs
-dimers phosphorylate each other
-recognized by adapter protein (SOS) that activates a G Protein RAS
-mediate interactions between cells
61
The Zona pellucida
the thick transparent membrane surrounding a mammalian ovum before implantation
62
During the process of congression...
microtubles bring pro nuclei toward each other fuse together
63
Fast block of polyspermy: Which of the following sentences is true
change in electric pot of egg cell membrane occurs immediately upon entry of sperm
-sperm cannot bind positive membranes
64
Sulfate polysaccharides of the egg jelly...
-initiates acrosome reaction
-polysacc binds to specific receptors located directly above acrosomal vesicle
-species specific
-binding activates calcium transports into sperm on sperm cell membrane na+/hex
65
Cells of the trophoectoderm
are nutrition cells that create the placenta/ICM cell
66
Is it correct to say that BMP signaling is...
1. BMP signaling is important for the development of bones and the mobilization of SMAD proteins
2. inhibited by noggin and chordin that bind directly to bmp
67
Lateral inhibition via juxtacrine signals...
1. can inhibit the signals from other cells
2. restricts adjacent cell fates
notch delta mediated mechanism
68
Cadherin cytoplasmic region...
cytoplasmic region highly conserved (regulate cell-cell binding of extracellular domain of e-Cadherin
69
The Zona Pellucida of a mouse is made of
3 major gycloproteins
70
The Zona Pellucida of a human is made of
4 major glycoproteins
71
Does the acrosome reaction happen before or after contact with ZP?
Before
72
Function of ZP2
allows sperm to thick
73
Function of ZP3
controls the binding of sperm to the ZP
74
Where does the junction between the inner acrosome mem. and egg happen at?
Equatorial region
