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Cell biology > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

intermediate filaments

A

provides mechanical strength and help cell resist shear stress

  • keratin
  • neuro filaments. helps hold axons in neurons
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2
Q

microtubules

A

aid in positioning of internal organelles and intracellular transport

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3
Q

actin filaments

A

help in shaping the cell and in whole cell locomotion

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4
Q

microtubules and actin filaments

A

are very dynamic. constantly changing.

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5
Q

sarcomere

A

from one z disk to another

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6
Q

making filaments

A
  • Made of small protein subunits
  • Subunits are held together by weak non-covalent interactions
  • Accessory proteins interact with filaments to allow for highly organized internal structures
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7
Q

filaments made as protofilaments

A
  • May be multiple long strings of subunits joined end to end and associate laterally
  • Twist around one another - makes them really stable and strong
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8
Q

of protofilaments
actin
microtubules
intermediate filaments

A

2
13
4

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9
Q

Stability also depends on the subunits
Actin
Intermediate filaments

A
  • has small globular subunits

- have longer subunits making them a little stronger

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10
Q

polar vs non polar filaments

A
  • not about interactions w aqueous envir

- polar (different ends) and non polar (same ends)

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11
Q

for the polar ends they call them + and - ends

A
  • they are not charge
  • things are going to be added added/subtracted faster on plus end
  • minus end can add but slower
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12
Q

microtubules - polar

A
  • alpha tubulin and beta tubulin

- form dimers to make protofilament

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13
Q

alpha tubulin and beta tubulin bind to

A

GTP (just changes shape). alpha tubulin doesnt hydrolyze, but beta tubulin hydrolyzes GDP and has different shape.

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14
Q

Multiple versions of the same protein

A

isoforms

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15
Q

centrosome (or MTOC)

A

is not an organelle bc it has no nucleus. non membrane bound

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16
Q

nocodazole

A

drug that inhibits formation of microtubule filaments. binds subunits and prevents polymerization

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17
Q

antibodies

A

highly specific proteins. They have shape of a Y. has disulfide bonds (formed by cysteine). They are tertiary structure. Antibodies stick on one end, on flurescent.

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18
Q

actin filaments are what?

A
  • polar
  • globular monomer called g-actin
  • g actin binds ATP
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19
Q

where are the plus ends?

A

on the outer part of microtubule

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20
Q

where are plus and minus ends on actin?

A

they are not organized. theyre everywhere.

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21
Q

centrifugal

A

going out. toward periphery

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22
Q

centripetal

A

going in. toward center

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23
Q

cortical actin

A

outer portion. allows for cell movement.

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24
Q

actin part 2

A

ropelike structures that provide strength and flexibility. important for motility and structure; highly dynamic structures

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25
intermediate filaments part 2
- not polar - not required in all cell types - coiled coil proteins - for structure - dont change - 2 monomers are parallel to each other in dimers - 2 dimers link together antiparallel to make tetramer (staggered)
26
tetramer is considered what?
protofilament- both ends look same | -need 8 parallel protofilaments to pack together 8x4=32 (strength) to make filament
27
what is protofilament?
string of g actins that are bound together
28
Type of intermediate filaments | axonal
neurons | -neurofilament proteins (help in organization)
29
Type of intermediate filaments | epithelial filaments
hair, nails, etc - Type I keratins (acidic) - Type II keratins (basic)
30
Type of intermediate filaments | Vimentin-like
- Desmin (muscle) - Vimentin (cells of mesenchymal origin) - Glial fibrillary acidic protein (glial cells) G fap - Peripherin (neurons)
31
Type of intermediate filaments | nuclear
(nuclear lamina) | -lamins A, B, C
32
dendrites
they receive info. send it to cell body and cell body determines what to do with it
33
desmin
intermediate filaments that help hold together the large myofibrils. sarcomeres made of actin and myosin.
34
muscle cells are
multinucleated. they glom together and there is no separation of nuclei. actin holds them together.
35
where are lamins located?
inner side of nuclear membrane. double membrane.
36
where are chromosomes inside nucleus?
bound to proteins on edge and to lamin.
37
why is it called chromatin?
chromosomes are bound by proteins. | ex histones. H2A, H2B, H3, H4. nucleosome
38
diseases of intermediate filaments | Epidermolysis bullosa simplex
defect in keratin. skin falling off. | -One nucleotide change- changes a leucine to a proline - disrupts 2nd structure (alpha helix)
39
Amyotrophic lateral sclerosis (ALS or Lou Gehrig’s Disease) -
accumulation and abnormal assembly of neurofilaments in motor neuron cell bodies Linked to SOD mutations - how it causes defects in neurofilaments not known
40
nucleation
how do filaments start in the first place
41
polymerization
growth | – Maintain length - treadmilling
42
breakdown
catastrophe. reorganization mitosis
43
kineticores
attach to chromosomes
44
salt
ionic. dissolves in water
45
3 diff phases
nucleation- lag phase. if theres no salt the subunits can bind to one another elongation- growth phase. gets bigger or smaller steady state- equilibrium phase. adding and removing at equal rates. how? based on # of subunits available.
46
The concentration of free subunits when the rate of
addition is equal to the rate of dissociation
47
If the number of subunits available is above the Cc
you will be making filaments
48
If the number of subunits available is below the Cc,
filaments will be depolymerizing
49
there are diff Cc for the
+ and - end of filaments
50
critical concentration based on
concentration of subunits available
51
treadmilling
- hydrolysis of ATP and GTP occurs continuously - Occurs slowly on monomers not incorporated into filaments - But, hydrolysis occurs rapidly once monomers are bound-ADP or GDP remain bound until removed - T-form (ATP or GTP) and D-form (ADP or GDP)
52
red in picture is actin
changing in course of time (moving but staying in same spot)
53
The longer g actins /microtubules are in it, more likely it will stay in
ADP or GDP bound form
54
more likely to add to
T form (ATP OR GTP)
55
cytosol is high in
ATP and GTP
56
free subunits are what form?
T form | -rate of addition affects whether the end is atp or gtp (ATP cap or GTP cap)
57
D form leans toward? | T form?
- disassembly | - assembly
58
addition at ___ end and removal at ___ end
+, -
59
soluble subunits are in what form?
T form
60
polymers are in waht form?
a mixture of T and D form
61
on the minus end, there are more
D forms. more likely to fall off. when you have T, less likely to fall off.
62
Treadmilling | yellow is the plus end bc you're adding
actin + atp. as they're moving through, they get hydrolyzed to adp.
63
polarity and size actin intermediate filaments microtubules
- yes, 8 nm - no, 10 nm - yes, 25 nm
64
Phalloidin
-binds to actin filaments and stabilizes them (from mushrooms). actin stays the way it was. -Comes from Amanita phalloides -Also known as “Death Cap” Two toxins -Amanitin – RNA pol II inhibitor, so no proteins -Phalloiden – binds f-actin and inhibits depolymerization of actin
65
Latrunculin
binds subunits and prevents polymerization (from sea sponge). actin disappears.
66
Cytochalasin D
- inhibits addition of monomers at the + end causing
67
taxol
used in cancer patients; binds and stabilizes microtubules (Yew tree bark); kills rapidly dividing cells (toxic)
68
Colchicine
binds free tubulin leading to microtubule depolymerization (meadow saffron or autumn crocus/flower)
69
Acrylamide (SDS-PAGE)
dismantles neurofilament bundles (intermediate filaments) in peripheral nerve axons and hence is a neurotoxin
70
acrylamide in your food?
its formed in food when asparagine reaction w certain sugars like glucose. only happens when temp during cooking is high
71
intermediate filaments do not do
protofilaments

Cell biology (15 decks)

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