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Molecular Biology - Unit 2 - Zach H. > Molecular Test 2 Review > Flashcards

Molecular Test 2 Review Flashcards

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1
Q

What is the function of tight junctions?

A

Seals gap between epithelial cells.

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2
Q

What is the function of adherens junctions?

A

Connects actin filament bundle in one cell with that in the next cell.

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3
Q

What is the function of the desmosome?

A

Connects intermediate filaments in one cell to those in the next cell.

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4
Q

What is the function of gap junctions?

A

Allow the passage of small water-soluble molecules from cell to cell.

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5
Q

What is the function of hemidesmosomes?

A

Anchors intermediate filaments in a cell to extracellular matrix.

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6
Q

What is the function of actin-linked cell-matrix adhesion?

A

Anchors actin filaments in cell to extracellular matrix.

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7
Q

Which cell junction type is a occluding junction?

A

tight junction

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8
Q

Which cell junction type is a cell-cell anchoring junction?

A

> adherens junction

> desmosome

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9
Q

Which cell junction type is a channel-forming junction?

A

gap junction

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10
Q

Which cell junction type is a cell-matrix anchoring junction?

A

> actin-linked cell-matrix adhesion

> hemidesmosome

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11
Q

Which three cell junctions form the junctional complex?

A

> tight junctions
adherens junction
desmosome

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12
Q

Which cell junctions do actin bind to?

A

> adherens junction

> actin-linked cell-matrix

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13
Q

Which cell junctions do intermediate filaments bind to?

A

> desmosome

> hemisesmosome

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14
Q

List the three anchor proteins that link classical cadherins to actin in the cytoskeleton?

A

> beta-catenin
gamma-catenin
p120-catenin

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15
Q

Which two cell types have cadherins as the principal components?

A

> adheren junctions
desmosomes

cluster at sites of cell-cell contract in most solid tissues

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16
Q

Classical cadherins?

A

Ca2+ dependent adherens junctions.

  • E-cadherin
  • N-cadherin
  • VE-cadherin
  • P-cadherin
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17
Q

Nonclassical cadherins?

A

Ca2+ dependent; form desmosome junctions, and the recently discovered large subfamily of protocadherins, which are implicated in neuronal plasticity

  • desmocollins
  • desmogleins
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18
Q

What are the two main tight junction proteins?

A

> claudin (main functional component)

> occludin

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19
Q

What protein anchors tight junctions to actin cytoskeleton?

A

ZO protein

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20
Q

List the 3 functions of tight junctions.

A

> barrier function
fence function
signaling function

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21
Q

What are the 3 conserved polarity proteins complexes that control polarization processes and maintain polarity?

A

> Par
Crumbs
Scribble

22
Q

What does formin do?

A

nucleates assembly and remains associated with the growing plus end

actin subunit accessory protein

23
Q

What does ARP complex do?

A

nucleates assembly to form a web and remains associated with the minus end

actin subunit accessory protein

24
Q

What does profilin do?

A

binds to subunits, speeds assembly

actin subunit accessory protein

25
Q

What does thymosin do?

A

binds to subunits, prevents assembly

actin subunit accessory protein

26
Q

What does cofilin do?

A

binds ADP-actin filaments, accelerates disassembly

actin filament accessory protein

27
Q

What does fimbrin, alpha-actinin, filamin, and EFM do?

A

filament bundling, cross-linking, and attachment to membrane

actin filament accessory proteins

28
Q

What does tropomyosin do?

A

stabilizes filament

actin filament accessory protein

29
Q

What does gamma-TuRC do?

A

nucleates assembly and remains associated with the minus end

microtubule accessory protein

30
Q

What does kinesin 13 do?

A

enhances catastrophic disassembly at plus end

microtubule filament accessory protein

31
Q

What does Tau and MAP-2 do?

A

filament bundling and cross-linking

microtubule filament accessory protein

32
Q

What does MAPs do?

A

stabilizing tubules by binding along sides

microtubule filament accessory protein

33
Q

What does XMAP215 do?

A

stabilizing plus ends and accelerates assembly

microtubule filament accessory protein

34
Q

After the first round of low-speed centrifugation in cell fractionation, what does the pellet contain?

A

> whole cells
nuclei
cytoskeleton

35
Q

After medium-speed centrifugation in the second round of cell fractionation, what does the pellet contain?

A

> mitochondria
lysosomes
perioxisomes

36
Q

After high-speed centrifugation in the third round of cell fractionation, what does the pellet contain?

A

> microsomes

> small vesicles

37
Q

After very-high-speed centrifugation in the fourth round of cell fractionation, what does the pellet contain?

A

> ribosomes
viruses
large macromolecules

38
Q

ion-exchange chromatography

A

+ charge beads

39
Q

gel-filtration chromatography

A

porous bead

40
Q

affinity chromatography

A

bead with covalently attached substrate

41
Q

Desensitization of Signal by hormone level dropping.

A

decrease AC activity -> decreased cAMP -> decreased PKA activity

42
Q

Desensitization of signal by removing signaling molecule.

A

phosphodiesterases (remove cAMP/cGMP)

43
Q

Desensitization of signal by receptor sequestration.

A

endosome

44
Q

Desensitization of signal by receptor destruction.

A

endosome + lysosome (proteases)

45
Q

Desensitization of signal by GRKs (G protein receptor kinases).

A

phosphorylate the receptor such that another protein called ARRESTIN will bind to the 3rd intracellular loop & prevents G-alpha from interacting with the third loop.

Result -> G-alpha-GDP does not get converted to G-alpha-GTP.

46
Q

How does arrestin desensitization of signals?

A

Binds to 3rd intracellular loop and prevents G-alpha from interacting with the 3rd loop.

47
Q

order of GPCR mechanism

A

GPCR -> trimeric Gs-protein -> adenylyl cyclase -> cAMP -> PKA -> enzyme -> substrate/product -> amplification

48
Q

Gs GPCR

A

Gs -> adenylyl cyclase -> cAMP -> PKA

49
Q

Gi GPCR

A

Gi -> inhibition of adenylyl cyclase -> no cAMP -> no PKA

50
Q

Gq GPCR

A

Gq -> PLC (cleaves PIP2) -> DAG and IP3:

IP3 -> Ca2+ release -> binds to PKC and calmodulin -> activate proteins

DAG -> PKC -> phosphorylation of target proteins

51
Q

Steps in RTK signaling.

A

1) growth factor binds and receptor dimerizes
2) autophosphorylation occurs
3) binding of adaptor proteins such as Grb2
4) complex assembly
5) guanine NT exchange
6) Ras binds to RAF and initiates MAP kinase pathway

Molecular Biology - Unit 2 - Zach H. (11 decks)

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