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MCB 3010 > quiz 4 > Flashcards

quiz 4 Flashcards

1
Q

gastrulation

A

early formation of different germ layers

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2
Q

blastocyst

A

inner mast cell - develops into outer layer (tropoblast and embryo) - becomes placenta in mammals

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3
Q

totipotent vs pluripotent

A

totipotent - can create a complete organism (placenta included)
pluripotent- cant

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4
Q

epigenetics

A

how a cell remembers what it should become based off of changes of structure of genome that permits certain genes to be opened or closed
1. combination control
2. cell memory

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5
Q

morphogen

A

long-range inductive signalling that exert graded effects (varies by conc)

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6
Q

AV axis

A

animal vegetal
-internal vs external

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7
Q

AP axis

A

anterior posterior
-head vs tail

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8
Q

DV axis

A

dorsal ventral
-back vs belly

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9
Q

when is AP axis determined

A

prior to fertilization (due to bicoid)

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10
Q

bicoid- how does it give rise to AP axis

A

at anterior pole, diffusion gradient away from point gives rise to AP axis

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11
Q

mechanisms of pattern formation- AP axis

A

-bicoid
-gap genes
-pair-rule
-segmental polarity

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12
Q

bicoid role, regulation and what happens if mutated

A

-gives head and tail (AP)
-prior to cellurization
If mut: lose segmentation

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13
Q

gap gene role, regulation and what happens if mutated

A

-subdivides core segments
-active when bipoid is low
If mut: gets head, tail and only one area in between

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14
Q

pair-rule role, regulation and what happens if mutated

A

-divides ares defined by GAP
(1/2 of each segment under influence of pair-rule)
-gap genes drive expression of pair role (co-exressed with Gap)
If mut: no segmentation of segments

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15
Q

segmental polarity genes (ie. Hedgehog) role, regulation and what happens if mutated

A

-gives polarity to each segment, so that 1/2 of each segment is not a mirror image of whats next to it
-pair-rule (?) further divides segments, drives segment polarity genes
If mut: all segments are the same

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16
Q

what do segmental genes do

A

control drosophila segmentation along AP

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17
Q

subdividing of drosophila embryo

A

-one cell makes and secretes wnt, -acts on neighbouring cell thru effector protein (engrailed)
-engrailed signals for synthesis and release of hedgehog
- hedgehog further promotes release of WNT
-after 3 dcell divisions along AP engrailed is stabalized and no longer needs WNT

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18
Q

hox

A

locks in and stabalizes patterning

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19
Q

what is hox controlled by and what 2 complexes does it function thru

A

WNT and HH
Bithorax complex (abdominal and thoracic)
Antennapedia complex ( thoracic and head)

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20
Q

loss of hox

A

cells that are all alike, can develop segments at wrong place

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21
Q

sequential gene activation

A

posterior genes inhibit anterior
-if most posterior gene is on, no other ones are
-changes in chromatin structure and sequential opening/closing of heterochromatin

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22
Q

trithorax

A

keep chromatin open once hox genes are on (most posterior gene dominant)

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23
Q

polycomb

A

keep chromatin closed in regions where hox is not expressed

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24
Q

mutation is esc gene

A

blocks polycomb, all chromatin pen and all hox genes on

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25
Q

nodal

A

TGFR activator, acts locally (diffuses slowly)
-more nodal active @ vegetal pole (V) becomes endoderm

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26
Q

lefty

A

SMAD inhibitor, acts distal to site of secretion (diffuses rapidly)
-more lefty active @ animal pole (A) becomes ectoderm

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27
Q

high BMP

A

epidermal tissue (ventral)

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28
Q

low BMP

A

neural tissue (dorsal)

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29
Q

noggin and chordin

A

TGF antagonist - SMAD inhibition
block BMP on dorsal side (not ventral) in gradient manner

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30
Q

active notch

A

stay projenitor

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31
Q

inactive notch

A

differentiate

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32
Q

stem cell

A

-can divide indefinitely,
-makes multiple cell types
-exists for entire life of the organism

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33
Q

progenitor cell

A

-divide a finite number of times
-have already specialized to make restricted cell type

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34
Q

embryonic stem cell

A

does not qualify by standard definition of stem cell - only exists for a short period of time

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35
Q

neural tissue comes from

A

ectoderm

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36
Q

neural cell formation

A

ectoderm –> neuroectoderm –> neural tube –> neural cells

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37
Q

signals needed for neural cell form

A

-cytoskeletal remodelling
-morphogens - receptor signalling
-chemoattractants/ repellants

38
Q

bending of epi cells facilitated by

A

actin/myosin contraction - mediated by Rho-GTPases

39
Q

notochord

A

releases many morphogens
-cells proliferate and migrate inwards –> differentiates based on proximity to notochord

40
Q

RhoA staining experiment

A

RhoA clusters toward surface of folds - acts on adhsion belt to cause contraction -invagination - closing of tube

41
Q

ROCK inhibitor

A

no contraction of actin adhesion belt = no invagination of neural tube

42
Q

2 WNT signaling pathways

A

canonical: B-catenin transcriptional co-activation
- generation of neural progenitors and specialized sub-types

non-canonical: dishevelled activates Rho/ROCK and alters cytoskeleton
-neural tube closure and cytoskeletal dynamics

43
Q

shRNA

A

gene silencing effect

44
Q

shRNA against frizzled

A

inhibition of Wnt

45
Q

morphogen spinal cord example

A

epi wall of neural tube thick –> forms small central channel
-different neurons form along DV axis
Motor neuron - ventral side
Sensory neuron - dorsal side

46
Q

Shh released from

A

floor plate (notochord), diffuses up

47
Q

BMP/Wnt released from

A

roof plate, diffuses down

48
Q

high WNT/BMP low Shh

A

sensory (dorsal)

49
Q

high Shh low WNT/BMP

A

motor (ventral)

50
Q

pax

A

divides neural projenitor cells into broad dorsal-ventral domains

51
Q

BMP what Pax

A

dorsal pax 3 and 7
inhibits ventral pax 6

52
Q

Shh what pax

A

ventral pax 6

53
Q

pax 6

A

activates neuronal (ectodermal) genes while repressing endodermal and mesodermal

54
Q

spinal cord further subdivided by expression of

A

basic helix-loop-helix (bHLH)
homeodomain (TFs)

55
Q

neural tube failure to close at top vs bottom

A

bottom - mild
top - no brain development, fatal

56
Q

radial glial cells

A

-specialized neuroectoderm cells
-functions as stem cell - can give rise to neurons and glia
-forms scaffhold on which neurons can migrate

57
Q

N-cam

A

neural cell adhesion molecule
-growth cone guidance thru cell surface adhesion

58
Q

NG2

A

chrondroitin sulfate proteoglycans
-inhibits growth cone migration thru contact inhibition

59
Q

commissural axons

A

travel from one side of body to another, coordinate movement

60
Q

commissural neurons in spinal cord

A

-commissural neurons send axons ventrally to floor plate
-drawn by a Netrin gradient (chemotaxis)
-Netrin secreted by floor plate
-Netrin then turns at right ang;e

61
Q

DSCAM

A

neighbours never express same DSCAM
-cadherins bind cadherins of same type
-in THIS case: binding = repulsion
-same DSCAM = repel

62
Q

dendrites and axonal branches from the same neuron ________ eachother

A

avoid

63
Q

autapses

A

self-synapse (axon syapses w own dendrite)

64
Q

synaptic pruning

A

synapse elimination

65
Q

endoderm tubes

A
  1. digestive - extend thru body; lover, pancreas, gallbladder
  2. respiratory - outgrowth of digestive tube; 2 lungs
66
Q

endoderm function

A

construct lining of tubes
gives bulk of internal organs

67
Q

pharynx

A

common chamber shared by tubes
-anterior region of embryo
-epithelial outpockets give rise to thyroid, tonsils, thymus, and parathyroid glands

68
Q

pharynx and pharyngeal pouches
within developing embryo:

A

-tubes w folds develop into organs
-fore, mid, hind gut
-pocket and offshoot develop: depends on position (how much Gf they are exposed to)

69
Q

purpose of crypts

A

1). constant/quick proliferation: protect lining from mutations

2). control signaling

70
Q

absorptive cell

A

dense layer of microvilli
-take in nutrients from lumen

71
Q

goblet cell

A

secrete protective coat of mucous
-secrete mucous into lumen

72
Q

paneth cell

A

gut immune response against bacteria
-secrete signal factors into lumen

73
Q

enteroendocrine cell

A

secrete hormones that help control appetite satiety and cell growth
-secrete hormones into blood - signal if there are nutrients present or not

74
Q

BrdU labelling is incorporated during _____ phase

A

S

75
Q

APC mutation

A

loss of scaffhold or gsk3b complex
-cant degrade beta catenin

76
Q

wnt secreted by

A

paneth cells

77
Q

what maintains notch expression

A

Wnt

78
Q

active Notch in presence of Wnt

A

cells proliferate and specify to transit amplifying cells

79
Q

block wnt

A

cells lose notch ; differentiate to absorptive cells

80
Q

active delta no wnt

A

differentiate to goblet/ secretory cells

81
Q

notch expression in crypt cells

A

expressed in all cells in crypt

82
Q

what cells express delta and what expresses notch

A

delta - paneth cells
notch - stem cells

83
Q

delta

A

inhibits notch cell from differentiating, differentiates into secretoary cell

84
Q

what if there was no notch

A

all cells in crypt would differentiate

85
Q

epithelial vs mesenchymal

A

Epithelial:
-apical-basal polarity
-contact w basal basement membrane
-extensive cell-cell contacts
-E-cadherin
-cyto-keratins (ECM)

Mesenchymal:
-anterior-posterior polarity
-absence of cell-cell junctions
-N-cadherin
-mesenchymal specific vimentin (ECM and integrin binding)

86
Q

WNT and TGFb to support EMT

A

TGFB - SMAD - drive expression of EMT-TFs (eg. snail)
WNT- Frizzled/b-catenin - activate EMT-Tfs thru GSK3b inhibition

INHIBITION OF GSK3B BLOCKS SNAIL DEGRADATION

87
Q

snail

A

active in nucleus
-represses E-cadherin
-drives expression of N-cadherin and vimentin (switch to mesenchymal)

88
Q

tumors and EMT

A

become more invasive and metastatic

89
Q

tumors EMT process

A

normal epi layer undergos EMT
- cells migrate out
- if accumulated mutation, cancer cells migrate

90
Q

when is DV axis defined

A

at the time of fertilization

91
Q

neurons must be ensheathed by ________ to facilitate communication over long distances

A

support cells (oligodendrocytes)

92
Q

chat gp

A

MCB 3010 (20 decks)

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