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Cell biology > Lecture 9 > Flashcards

Lecture 9 Flashcards

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AP® Biology flashcards Biology 101 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
Q

intermediate filaments part 2

A
  • 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)
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26
Q

tetramer is considered what?

A

protofilament- both ends look same

-need 8 parallel protofilaments to pack together 8x4=32 (strength) to make filament

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27
Q

what is protofilament?

A

string of g actins that are bound together

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28
Q

Type of intermediate filaments

axonal

A

neurons

-neurofilament proteins (help in organization)

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29
Q

Type of intermediate filaments

epithelial filaments

A

hair, nails, etc

  • Type I keratins (acidic)
  • Type II keratins (basic)
30
Q

Type of intermediate filaments

Vimentin-like

A
  • Desmin (muscle)
  • Vimentin (cells of mesenchymal origin)
  • Glial fibrillary acidic protein (glial cells) G fap
  • Peripherin (neurons)
31
Q

Type of intermediate filaments

nuclear

A

(nuclear lamina)

-lamins A, B, C

32
Q

dendrites

A

they receive info. send it to cell body and cell body determines what to do with it

33
Q

desmin

A

intermediate filaments that help hold together the large myofibrils. sarcomeres made of actin and myosin.

34
Q

muscle cells are

A

multinucleated. they glom together and there is no separation of nuclei. actin holds them together.

35
Q

where are lamins located?

A

inner side of nuclear membrane. double membrane.

36
Q

where are chromosomes inside nucleus?

A

bound to proteins on edge and to lamin.

37
Q

why is it called chromatin?

A

chromosomes are bound by proteins.

ex histones. H2A, H2B, H3, H4. nucleosome

38
Q

diseases of intermediate filaments

Epidermolysis bullosa simplex

A

defect in keratin. skin falling off.

-One nucleotide change- changes a leucine to a proline - disrupts 2nd structure (alpha helix)

39
Q

Amyotrophic lateral sclerosis (ALS or Lou Gehrig’s Disease) -

A

accumulation and abnormal assembly of neurofilaments in motor neuron cell bodies

Linked to SOD mutations - how it causes defects in neurofilaments not known

40
Q

nucleation

A

how do filaments start in the first place

41
Q

polymerization

A

growth

– Maintain length - treadmilling

42
Q

breakdown

A

catastrophe. reorganization mitosis

43
Q

kineticores

A

attach to chromosomes

44
Q

salt

A

ionic. dissolves in water

45
Q

3 diff phases

A

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
Q

The concentration of free subunits when the rate of

A

addition is equal to the rate of dissociation

47
Q

If the number of subunits available is above the Cc

A

you will be making filaments

48
Q

If the number of subunits available is below the Cc,

A

filaments will be depolymerizing

49
Q

there are diff Cc for the

A

+ and - end of filaments

50
Q

critical concentration based on

A

concentration of subunits available

51
Q

treadmilling

A
  • 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
Q

red in picture is actin

A

changing in course of time (moving but staying in same spot)

53
Q

The longer g actins /microtubules are in it, more likely it will stay in

A

ADP or GDP bound form

54
Q

more likely to add to

A

T form (ATP OR GTP)

55
Q

cytosol is high in

A

ATP and GTP

56
Q

free subunits are what form?

A

T form

-rate of addition affects whether the end is atp or gtp (ATP cap or GTP cap)

57
Q

D form leans toward?

T form?

A
  • disassembly

- assembly

58
Q

addition at ___ end and removal at ___ end

A

+, -

59
Q

soluble subunits are in what form?

A

T form

60
Q

polymers are in waht form?

A

a mixture of T and D form

61
Q

on the minus end, there are more

A

D forms. more likely to fall off. when you have T, less likely to fall off.

62
Q

Treadmilling

yellow is the plus end bc you’re adding

A

actin + atp. as they’re moving through, they get hydrolyzed to adp.

63
Q

polarity and size
actin
intermediate filaments
microtubules

A
  • yes, 8 nm
  • no, 10 nm
  • yes, 25 nm
64
Q

Phalloidin

A

-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
Q

Latrunculin

A

binds subunits and prevents polymerization (from sea sponge). actin disappears.

66
Q

Cytochalasin D

A
  • inhibits addition of monomers at the + end causing
67
Q

taxol

A

used in cancer patients; binds and stabilizes microtubules (Yew tree bark); kills rapidly dividing cells (toxic)

68
Q

Colchicine

A

binds free tubulin leading to microtubule depolymerization (meadow saffron or autumn crocus/flower)

69
Q

Acrylamide (SDS-PAGE)

A

dismantles neurofilament bundles (intermediate filaments) in peripheral nerve axons and hence is a neurotoxin

70
Q

acrylamide in your food?

A

its formed in food when asparagine reaction w certain sugars like glucose. only happens when temp during cooking is high

71
Q

intermediate filaments do not do

A

protofilaments

Cell biology (15 decks)

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