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Advanced Cells > lec 6-7 cell cycle and cell polarity > Flashcards

lec 6-7 cell cycle and cell polarity Flashcards

(54 cards)

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1
Q

defects in cell division

A

lead to chromosome abnormalities

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2
Q

when is the genome replicated (eukaryotic)

A

S phase

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3
Q

what is the order of the cell cycle

A

G1
S
G2
M

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4
Q

G1

A

commitment to cell division

cell grows in size
synthesises mRNA and proteins (histones) required for DNA synthesis

checkpoint before S phase

  • formation of G1/S cyclin with Cdk
  • is environment suitable e.g. pH
  • integrity of DNA assessed
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5
Q

if a cell does not clear to pass through to S phase..

A

enters G0, dormant phase

- no cell growth or division

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6
Q

G2

A

rapid cell growth and protein synthesis

preparation for mitosis

checkpoint:
G2/M
- checks for damage

if damage signals activate p53
Cdk1 inhibited
cell cycle does not progress

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7
Q

hartwell discovered

A

checkpoints using budding yeast

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8
Q

paul nurse discovered

A

cdk and regulators using fission yeast

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9
Q

hunt discovered

A

cyclins using sea urchins

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10
Q

Wee1

A

kinase
influences cell size
inhibits entry of cell cycle into mitosis
inhibits cdk1 by phosphorylation

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11
Q

proteolysis

A

degradation of a protein

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12
Q

mitosis

A

segregation of equal numbers of chromosomes into each daughter cell

2 genetically identical daughter cells

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13
Q

outline steps of mitosis

A 
DNA condenses
centrosome duplicates
microtubules terminate and attach to chromosomes
chromosomes align on mitotic spindle 
separate to opposite ends
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14
Q

3 types of microtbule making up mitotic spindle

A

astral
interpolar
kinetochore

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15
Q

astral microtubules

A

anchor the spindle poles to the cell membrane

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16
Q

interpolar microtubules

A

overlap/interlock and the spindle midzone

keep poles at correct distance apart

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17
Q

kinetochore microtubules

A

mediate attachment of kinetochore microtubules to chromosome via kinetochore complex (attachment site)

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18
Q

chromosome movement

A

microtubule polymerisation

kinetochore microtubules shorten and draw chromosomes towards spindle poles

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19
Q

role of microtubules in cytokinesis

A

position plane of division

contractile ring drives cleavage (actin and myosin motor protein also involved)

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20
Q

s phase

A

DNA replication

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21
Q

M phase

A

mitosis - nuclear division
cytokinesis - cytoplasmic division

checkpoint 3 - are all chromosomes properly attached to mitotic spindle?

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22
Q

activation of cdk

Study These Flashcards
A

activated by cyclins

cyclin concentration oscillates during cell cycle

causes cell cycle to progress

23
Q

cdc2

Study These Flashcards
A

cell division cycle protein 2 - same as cdk1

24
Q

negative regulator of cell division

Study These Flashcards
A

Wee1 - kinase

25
Cdc25
phosphotase positive regulator of cell division stimulates cdc2/cdk1 progression of cell cycle
26
ndc80
protein ring complex attaches to kinetochore and microtubule leaves space in between for microtubule polymerisation
27
amphitelic attachment
- Each kinetochore is attached to microtubules from opposing spindle poles - monomers of intermediate filaments interact in both parallel and anti-parallel manners to form dimers
28
syntelic attachment
- Both sister kinetochores are attached to MTs from the same spindle pole
29
monotelic
- One kinetochore is attached to a MT from a spindle pole and the other kinetochore is not attached to a MT
30
spindle assembly checkpoint - SAC
in M phase | checks all microtubules are properly attached to the spindle
31
polarity
having one end morphologically/funcionally different from the other
32
why is polarity necessary
cellular morphogenesis tissue morphogenesis organism morphogenesis
33
4 main examples of polarisation mechanisms
neuronal guidance assymetrical cell division yeast mating cell migration
34
how is cell polarity acheived
cytoskeletal remodelling signal pathways converge on actin and microtubule cytoskeletons reassembly of filaments at new sites
35
taxis
motion of orientation of a cell/organism in response to an external stimulus
36
GEFs
proteins that activate GTPases by stimulating release of GDP
37
GDIs
bind to GDP-bound GTPases and prevent exchange
38
guidance cue
something that attracts or repels the cell either contact/adhesion or chemical recognised by receptors on growth cones (structure at tip)
39
contact/adhesion guidance cues
proteins form a substrate on which the cell can crawl ECM often short-range e.g. cadherins attract
40
chemical guidance cues
secreted often long-range e.g. netrins attract, semaphorins repel
41
commissural neurons
use guidance cues to project onto the other side of the CNS | ensure left-right synchronisation
42
DDC receptors for netrin
once activated, lead to signal cascade | growth cones crawls in direction of ventral midline in brain
43
slit protein
has opposite effect to netrin, prevents neurons crossing midline again secreted by floor plate
44
role of GPCR
to transduce an extracellular signal to a small GTPase to cause a cellular response
45
examples of small monomeric GTPases
Rho | Ras
46
substrate level phosphorylation
metabolic process | results in ATP/GTP formation by direct transfer of a phosphate group
47
central regulator or cell polarity
cdc42
48
par proteins
responsible for asymmetric positioning of mitotic spindle help polarise tissues relocalise over time e.g. LBK1 is a human par protein
49
epithelial apical-based polarity
plasma membrane of epithelial cells is divided into two domains splits top and bottom
50
what separates apex and baso-lateral surface
tight junctions
51
apical surface
permeable to water-soluble molecules surface area can be increased faces externally
52
basolateral surface
impermeable faces internally in contact with blood supply
53
2 complexes associated with par proteins
scribble and crumbs
54
role of par proteins
kinases - switch other proteins on/off | scaffolding factors interact and recruit other proteins

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