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Biochemistry and Cell biology > Week 3 > Flashcards

Week 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what determines cell shape/form

A

physical stress on walls, will change rigid/flexible

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2
Q

functional purpose of a cytoskeleton

A

provides framework for cell form and function

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3
Q

how to increase intermediate filament stability?

A
  • increasing number of filaments associated and sorting into stable conformations
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4
Q

properties of intermediate filaments?
- length
- polarity
- remodeler of IMFs?
- mechanism of IMF growth?

A
  • 10 nm
  • apolar
  • remodeled by phosphorylation
  • growth via lateral exchange
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5
Q

briefly describe the role of cytoskeleton of muscle cells

A

supports large shape changes

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6
Q

role of cytoskeleton in epithelia?

A
  • aid in polarization, barrier formation
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7
Q

role of cytoskeleton in neurons

A
  • drives polarity, shape changes
  • Microtubule system uses cytoskeleton to transport nts
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8
Q

what proteins mediate dynamic polarity of cells?

A

actin, tubulin

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9
Q

what is the difference (in terms of function) between basal and apical membrane of epithelial cells?

A

Apical– allow Na driven symport of glucose into the cell
Basal– allow diffusion of glucose out of cell into extracell fluid

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10
Q

purpose of polarity in cells (ex. in the event of to different concentrations on either side of cell)?

A

to ensure that cell function is directionally defined

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11
Q

what protein constitutes the brush border of epithelial cells?

A

actin filaments

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12
Q

purpose of capping actin filament ends?

A
  • confer stability– preventing dynamic remodeling
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13
Q

in cochlear hair cells, what proteins constitute stereocilia
- describe stereocilia response mechanism to sound

A
  • actin bundles, which tilt in response to sound
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14
Q

what motor protein is responsible for the mediating thin, thick actin filament movement in a sarcomere

A

myosin motor protein

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15
Q

describe the polarized actin distribution in filopodia (leading edge of a crawling cell)

A
  • tight parallel bundle
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16
Q

describe the role of actin in the fate of opsonized bacteria

A
  • actin is crucial in assembling/isolating and degrading opsonized bacteria during phagocytosis
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17
Q

what 3 location make up junctional complex

A
  • tight junction
  • adhesion belt
  • desmosome
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18
Q

what junction/complex mediates adhesion of the cell to cell matrix proteins and is associated with intracellular actin?

A
  • focal adhesion
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19
Q

describe adheren (cell-cell) junction in terms of:
- transm linker protein
- ligand
- intracell cytoskeletal attachment

A
  • cadherin
  • cadherin in neighboring cell
  • actin filaments
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20
Q

describe Desmosome junctions in terms of:
- transm linker protein
- ligand
- intracell cytoskeletal attachment

A
  • desmoglein/collins, cadherins
  • cadherin in neighbor cell
  • intermediate filaments
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21
Q

describe (cell-matrix) junction in terms of:
- transm linker protein
- ligand
- intracell cytoskeletal attachment

A
  • integrin
  • extracell matrix proteins
  • actin filaments
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22
Q

describe hemidesmosome junctions in terms of:
- transm linker protein
- ligand
- intracell cytoskeletal attachment

A
  • integrin (a6b4)
  • extracell. matrix
  • intermediate filaments
23
Q

what do adhesion molecules (cadherins) and signaling molecules (RAS) have in common (in terms of disease causing)?

A

they are both oncogenic

24
Q

purpose of targeting microtubule therapeutically?
i.e. what are MTs important for
- effect of medication on mt?

A

mts are important in cell division
- medication tries to confer mt stability

25
Q

describe Taxol and its therapeutic target/effect?

A
  • obtained from pacific yew, – used in breast, lung cancer treatment (paclitaxel)
  • encourages mt bundle formation
26
Q

genetic mutation in what cytoskeletal genes can lead to deafness, blindness?

A
  • mutations in myosin, kinesin-type motors
27
Q

describe the characteristics of intermediate filament (IMF) assembly
- energy requirement for polymerization
- types of structures formed
- head/tail domain

A
  • robust proteins (require denaturants to dissolve)
  • IMF polymerization is energy free
  • assembly into apolar higher oligomers
  • head essential/tail contributes to filament assembly
28
Q

describe the structure formation of alpha helical rod domain of IMFs

A
  • assembles first into Parallel dimers, then antiparallel tetramers
29
Q

describe the formation of coiled-coil in IMF protein dimers

A
  • coiled coil formation occurs due to heptad repeats in alpha helices
30
Q

where on IMFs does subunit exchange occur

A
  • subunit exchange occurs along the entire filament
31
Q

describe the order in which an IMF protofilament is formed

A

parallel dimer assembly–antiparallel tetramer assembly— tetramers assemble to form a protofilament

32
Q

distinguish between type 1/2 keratin IF proteins (most abundant type of IF)

A

1- acidic, isoelectric– lower molecular weight
2- neutral/basic– higher molecular weight

33
Q

which type 1/2 basal cell keratins are, when mutated, implicated in skin blistering (epidermolysis bullosa simplex)?

A
  • K5 (typeII)
  • K14 (Type I)
34
Q

what property allows for keratin IFs to be dynamic

A
  • soluble keratins that can be incorporated into filaments
35
Q

what facilitates nuclear assembly/disassembly during mitosis?

A

phosphorylation of key proteins

35
Q

characteristics of Lamin IFs?
- location
- bonus: difference between A, B type and what they form?

A
  • found in all nuclei
  • only found intranuclear
  • A type– all nuclei, B type– differentiated cells
    – form framework for nuclei lamina
36
Q

briefly describe cross linking system that links lamin IF (nuclear interior) with cytoplasmic components.
- what other filaments involved
- what proteins involved

A
  • IF network linked to cytoskeleton via plakins
    plakins connect cytoskeletal filaments (actin, mt, IFs) to each other/junctional complexes
  • plakins to nuclear interior via KASH–SUN domain proteins–> which bind to nuclear lamina in nucleus
37
Q

describe role of lamin in nuclear pore formation

A
  • lamin, lamin associated proteins (LAPs) anchor nuclear pore complex to nuclear membrane
38
Q

what IF surrounds sarcomere in skeletal muscle (hint: part of vimentin like filament family)?

A

Desmin

39
Q

role of profilin in actin assembly
- control of elongation?
- where does it complex associate
- effect on critical concentration

A

binds G-actin/ATP, associating it to barbed end
- prevents spontaneous elongation
- lowers critical concentration

40
Q

Role of capping protein in actin filament polymerization

A
  • stops elongation at barbed ends
41
Q

what is a unique property of ubiquitous protein profilin

A

has nucleotide exchange factor capabilities helps to maintain ATP pool

42
Q

role of thymosin beta 4 in actin filament assembly (beta4 most common isoform in mammals)

A
  • sequesters G actin, thereby preventing polymerization
  • ensures there is an actin pool ready once barbed end becomes uncapped
43
Q

difference in dynamic regulation of actin and tubulin networks?

A

Actin assembly involves ATP, tubulin requires GTP

44
Q

describe the role of ARP2/3 complex in actin filament assembly
- where does it associate

A
  • associates at minus end and conducts elongation of branch filaments
45
Q

result of upregulation of actin isoform beta-actin on cell movement

A
  • increases cell movement
46
Q

location of gamma, alpha actin?

A
  • gamma— cell periphery
  • alpha— stress fibers
47
Q

role of spectrin in actin filaments?

A
  • provides scaffold at plasma membrane/cortex
48
Q

effect of Rho hormone on actin configuration?

A
  • causes stress fiber formation/focal adhesions (internal of cell is streaked)
49
Q

effect of Cdc42 on actin configuration

A

filopodium formation (thin,spiky projections)

50
Q

effect of RAC on actin configuration

A
  • lamellipodium formation (flat, spread out)
51
Q

consequences of Rho activation (Rho-GTP)
- on formin/crosslinking
- myosin activity?
- cofilin
- stress fiber formation
- focal adhesions/integrins

A
  • increased crosslinking, myosin activity
  • stress fiber formation
  • inhibition of cofilin
  • increased focal adhesion formation, integrin clustering
52
Q

result of RAC activation (Rac-GTP)
- effect on myosin activity, ARP, Filamin, PIP2

A
  • decreased myosin activity
  • increased filamin crosslinking
  • increased branching
  • promotes PIP2 inhibition of capping protein— allows branching in lamellipodium

Biochemistry and Cell biology (6 decks)

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