Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CSD > Membrane_dynamics > Flashcards

Membrane_dynamics Flashcards

1
Q

Three aspects of membrane dynamics

A

Membrane fusion, fission, and curvature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Three classes of membrane fusion and an example of each

A

Cell-cell fusion (sperm-egg), host-pathogen (viral infection) and intracellular fusion (neurosecretion/exo-endo cytosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Steps in membrane fusion (4)

A
  1. Adhesion (targeting)
  2. Stalk intermediate
  3. Hemifusion
  4. Fusion pore (opening)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are different stages of membrane fusion assayed? (2)

A

Content dye, lipid markers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What dictates specificity during membrane fusion?

A

For viruses- HA1, binds to sialic acid on host cell

For vesicles - Rab GTPases, tethers, SNAREs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Methods to study fusion

A
  1. Mixing of fluorescent dyes

2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is the repulsive force of the two bilayers overcome?

A
  1. By the force of fusogenic proteins and their interacting factors (ie SNAREs and NSF/SM/SNAP)
  2. Charge gradient?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the nature of the hole that opens between the two bilayers?

A

Up for debate - whether it is formed by lipids only, lipids+SNAREs, more study needed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is membrane fusion regulated?

A

In neurosecretion - Ca and Ca binding proteins, activates docked synaptic vesicles
Could also be fusion protein modification, synthesis or degradation, or protein targeting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What defines influenza virus subtype?

A

HA fusion protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Is pH within endosomes very high or very low, or in between?

A

Very low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What environmental factor triggers HA conformational change?

A

pH change, allows for extension of coiled coil structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

HIV entry mechanism

A

Attaches to CD4, binds chemokine receptor, membrane insertion, conformational change, fusion, and entry of viral nucleocapsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Antiviral drug strategy for HIV (enfuvirtide)

A

Hairpin inhibitor that prevents conformational change of fusion proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Two types of SNARES and an example of each

A

T-SNARES (target membrane)
- syntaxin
V-SNARES (vesicle)
- VAMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Proteins that help SNAREs drive membrane fusion

A

NSF (chaperone), SNAP (soluble NSF attachment, (SM)

17
Q

What structure do SNAREs form between vesicle and target membrane

A

stable 4-helix bundles (parallel coiled coil)

18
Q

How was it shown that SNAREs are sufficient to drive fusion?

A

reconstitute SNAREs into liposomes and examine fusion by de-quenching

19
Q

Issue with in-vitro SNARE reconstitution

A

Needed a super high concentration in order to do anything, which is how people identified a positive regulator of SNARE action - SM proteins

20
Q

Mechanism of SM action

A

Form stable complex with SNARE complex, push reaction forward to drive membrane fusion even at high concentration

21
Q

Difference between cis and trans-SNARE complexes

A

cis-SNARE conformation exists after membrane fusion, no force applied
trans-SNARE exert inward force in order to create pore

22
Q

Recycling factors for future rounds of membrane fusion

A

NSF / SNAP (? - double check this)

23
Q

hemifusion

A

lipid mixing but not content mixing

24
Q

Function of NSF chaperone and SNAP

A

disassembly of SNARE complex

25
Q

What are diff types of membrane division? (4)

A

Cell division, intracellular vesicles pinching off, organelle division, formation of multi-vesicular bodies

26
Q

Two classes of membrane fission mechanisms and an example of when you see them

A

Pinch from outside (dynamin-related GTPase driven during mito division)
Pull from inside (actin/myosin filaments of contractile ring in cytokinesis)

27
Q

What is the role of dynamin in endocytosis

A

Assembles onto neck of fusion pore created by plasma membrane invaginations, squeezes (powered by GTPase) to release vesicle

28
Q

Does dynamin function as a “pinchase” or a “poppase”

A

who knows

29
Q

What protein group mediates division/fusion of mitos

A

Dynamin-related GTPases (DRPs)

30
Q

ESCRT

A
  • membrane budding and fission complex, important with multi-vesicular body formation, cytokinesis, and viral budding
  • sufficient for formation of intraluminal vesciles
31
Q

Three ways in which vesicles can be formed

A

Filament assembly
Protein conf change
GTP hydrolysis

32
Q

Different phospholipid shapes largely driven by (3)

A
  • Size of head group
  • Number of fatty acid chains
  • Shape of fatty acid chains (dependent on saturation state)
33
Q

Negative curvature dominated by what shaped lipids

A

cone-shaped

34
Q

Enzymes that can change shape of lipids

A

phospholipase (alter), acyl transferases (invert)

35
Q

Ways to curve a membrane (5)

A
  1. Insert small protein in one side of membrane
  2. Scaffold membrane
  3. Lipid composition
  4. Transmembrane proteins
  5. Cytoskeleton

CSD (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions