Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

bio 2b03 > module 5 > Flashcards

module 5 Flashcards

(49 cards)

Start Studying
1
Q

question: what’s the difference in func. between RER and SER?

A

RER
- co-translational transport
- prot. mod.
- formation of vesicles that will transport prot. from ER to golgi

SER
- fatty acid and phospholipid synthesis
- place of carb. metabolism
- place where calcium is sequestered or collected to regulate calcium conc. in the cytosol

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

question: what are the post-translational mod. that can happen in the ER? (4)

A
  1. glycolysation
  2. forming disulphide bonds
  3. prot. folding
  4. proteolytic cleavage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

question: what is protein glycolysation?

A
  • adding polysaccharide/sugar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

question: what is N-linked glycolysation

A
  • adding polysacch. to NH2 of asparagine
  • modified part of the prot. stays on luminal side throughout transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

question: what are disulphide bonds?

A
  • covalent bonds between SH groups of 2 cysteine AA
  • help form tertiary or quaternary struc.
  • give stability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

question: where do disulphide bonds occur?

A
  • in ER lumen
  • ER lumen = oxidizing envrt. = good for disulfide bonds (cytoplasm envrt. = opposite)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

question: what is the purpose of disulphide bonds?

A
  • common prot. on outside surface of cell mem.
  • bc more harsh and denaturing conditions outside
  • so bonds can provide more stability
    ⤷ help prot. stay folded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

explain: example of prot. with disulphide bridges

A
  • pancreatic ribonuclease A (RNAse A)
  • has 4 disulfide bridges
  • acidic conditions of intestine cause prot. to unfold but disulfide bonds help maintain struc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

question: what is protein disulphide isomerase?

A
  • resident ER prot.
  • promotes oxidation = good for disulphide birdge formation
  • can also correct incorrect disulphide bridge formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

question: how does PDI help form disulphide bonds?

A
  • PDI forms intermediate w/ cysteine AAs to accelerate rxn
  • oxidized PDI has a disulphide bridge
  • PDI forms intermediate w/ one of the cysteines
    ⤷ facilitates bond forming
  • PDI converts back to oxidized form in ER lumen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

question: what are lectins?

A
  • recog. mod/ proteins and assit prot. folding
  • like chaperones
  • ex. calnexin and calreticulin
    ⤷ calnexin in ER mem.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

question: what is BiP?

A
  • ER resident prot.
  • can recog. and bind to unfolded prot.
  • binds prot. when they appear on luminal side of ER during co-translational transport
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

question: what is proteolytic cleavage?

A
  • cleavage of peptide backbone of a prot.
  • ex. all type I integral mem. prot. have N-term. sig. seq. cleaved by signal peptidase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

question: what is the unfolded prot. response for?

A
  • when RER = overwhelmed by unfolded prot.
  • bc unfolded prot. can’t leave until properly folded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

question: how would the UPR respond?

A
  • 2 resp.:
    1. cell tries to restore normal cell func.
    ⤷ slowing down prot. translation
    ⤷ removing unfolded prot. for degradation
  1. increase prod. of chaperones to help fold
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

question: what prot. are essential in UPR in ER + why?

A

BiP
- BiP serves as chaperone to assit in folding + prevent aggregation

Ire1
- forms homodimers in ER mem.
⤷ only when active (not bound to BiP)
- serve as activated endonucleases
⤷ makes cuts in nucleic A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

question: how do endonucleases work (explain w/ Hac1)?

A
  • make internal cuts in nucleic acids ex. mRNA
  • Ire1 specifically targets Hac1
  • Hac1 = spliced to remove translation inhibition and allow synthesis of Hac1 prot.
  • Hac1 prot = transcription factor to activate transcription for BiP, lectins, PDI, signal peptidases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

explain: pulse-chase experiment

A
  • tagging prot. for short period time
  • only some prot. labeled
  • acinar cells (pancreas) incubated in a medium w/ radioactive methionine that would only be incorporated as they are translated into RER
  • cells removed after 3 mins, washed and moved to new medium w/out radioactive
  • chase gets visualized to see diff. stages from RER to apical surface of cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

question: what were the results of the pulse-chase experiment?

A
  • found that transport order:
    ⤷ radioactive prot.
    ⤷ through golgi complex
    post. golgi transport vesicles
    ⤷ secretory vesicles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

question: what were the results of the VSV TEM and GFP?

Study These Flashcards
A
  • vesicular stomatitis virus G-prot = tagged w/ GFP -> VSV-G:GFP prot.
  • at permissive T: prot. variant folds
  • at restrictive T: prot. variant denatures + stays in ER by UPR

INFECT CELLS
- at permissive T: GFP folds and transports out of ER
- at restrictive T: GFP retained in ER

21
Q

question: what is the yeast saccharomyces cerevisiae system for prot. transport?

Study These Flashcards
A
  • S.cerevisiae metabolizes sucrose by hydrolysis from prot. = invertase (secreted by yeast)
  • hydrolysis prod. glucose and fructose
  • gluc. + fruc. moved into cell to feed it
22
Q

question: what was the experiment on yeast prot. transport?

Study These Flashcards
A
  • random mut. in yeast genomes
  • looked for temp. sensitive mut. that failed to secrete invertase at restrictive T
  • causes invertase to accumulate
23
Q

question: what was the result of the experiment on yeast prot. transport?

Study These Flashcards
A
  • invertase accumulated at diff. regions depending on which parts of pathway were defective

INTERTASE IN CYTOSOL ONLY
- means defect in first step of prot. transport
⤷ co-translational transport to ER
- mut. to any part of ER translocon, SRP prot., SRP recep.

24
Q

question: what are the classes of secretory mutants that cause prot. to accumulate? (5) + where do they cause invertase to accumulate?

Study These Flashcards
A
  1. class a mutants
    ⤷ accumulate in cytosol
  2. class b mutants
    ⤷ accumulate in ER
  3. class c mutants
    ⤷ accumulate in ER to golgi transport vesicles
  4. class d mutants
    ⤷ accumulates in golgi
  5. class e mutants
    ⤷ accumulates in secretory vesicles
25
question: what is the pathway for prot. from RER to cell mem.?
- prot. leave RER in vesicles - through ER -> golgi complex -> cell mem **from ER, can go towards cis-cisternae or away from trans-cisternae - trans = constitutive and regulated secretory
26
question: what is the golgi complex composed of?
- long flat sacs = cisternae - can be cis or trans cisternae
27
question: what's the diff. between constitutive and regulated secretory pathways?
CONSTITUTIVE - for prot. released immediately after synthesis and transport - move from trans-golgi to cell mem. REGULATED - for prot. that are kept in cell until sig. trigger - held in secretory granules
28
define + explain: anterograde transport
- mvt. of prot. from RER to cell mem. - forward direction (away from nucleus) - correct model: prot. stay in cisternae and cisternae move through golgi complex
29
question: what is the cisternal maturation model/cisternal progression model?
- model B - prot. stay in cisternae - cisternae themselves move
30
question: why was model A favoured over B for anterograde transport?
- A = vesicles carry prot. and move from cis to med. and med. to trans - B = prot. stay in cisternae and cisternae move B correct bc: - prot. not in vesicles - prot. found on med. golgi ⤷ and if cisternae move, med.eventually becomes trans
31
question: what are the steps to vesicular trafficking? (4)
1. budding ⤷ vesicles form ⤷ buds arise from mem. of donor compartment 2. loading ⤷ cargo prot. loaded into buds 3. release ⤷ vesicles form + release 4. docking + fusion ⤷ fuse to mem. of recipient
32
question: what are the vesicles used in prot. transport?
1. clathrin coated 2. COPI coated 3. COPII coated
33
question: when are each type of vesicle required in the vesicular transport process?
- clathrin for transport away from trans-golgi to endosomes and cell mem. - COPI for retrograde (from golgi to ER) - COPII for transport from RER to cis-golgi
34
explain: vesicle budding in COPII vesicles
- 1st step - Sar1-GDP = inactive cytosolic prot. - Sec12 = transmem. prot. of donor (ER) - Sec12 = GEF so it facilitates GDP -> GTP on Sar 1 ⤷ activates Sar1-GTP - reveals N-term of Sar1 that anchors it to mem. of ER - COPII accumulates on donor mem. compartment ⤷ amount dep. on ability to bind w/ Sar1
35
explain: cargo loading in COPII vesicles
- 2nd step - bud = curved - cargo natually accumulates - cargo recep. accumulate in bud ⤷ bc coat prot. interacting w/ cytosolic domains of recep. of cargo
36
explain: vesicle release in COPII vesicles (w/out uncoating)
- 3rd step - GTP hydrolysis turns Sar1-GTP -> Sar1-GDP - releases Sar1 and coat prot. (uncoating) - uncoated vesicle = loaded w/ cargo - motor prot. recog. uncoated vesicle - moved to recipient mem.
37
question: what would happen if uncoating was prevented? how is uncoating prevented?
- collection of accumulating coated vesicles - prevents vesicle transport, docking, cargo unloading ⤷ coat is blocking req. prot. - adding non-hydrolyzable GTP or mut. of SarGTP prevents uncoating
38
question: how is a vesicle uncoated?
- clathrin coat = lattice - dynamin releases coat - GTPase hydrolyzes GTP -> GDP -> dynamin changes shape - release via pinchase or poppase
39
question: what are the poppase and pinchase models and how do they matter in uncoating?
- poppase = dynamin elongates + pushes vesicle away - pinchase = dynamin contricts and squeezes mem. to initiate release - both modles have evi. to be "correct"
40
explain: basics of fruit fly vesicle model
- vesicle formed during endocytosis at cell mem. of presynaptic neural cell ⤷ assisted by dynamin - shibire gene codes for dynamin - shibire = temp. sensitive
41
question: what happens to dynamin at diff. temps.? what happens to the fly?
- permissive T = dynamin expressed, folded, functional - restrictive T = dynamin denature, nonfunctional (no vesicle formation) - restrictive T = fly paralyzed
42
explain: vesicle docking and fusion in secretory vesicles
- Rab GTPase controls vesicle docking - Rab-GDP = free in cytosol - Rab-GTP = bound to vesicles - Rab on vesicle mem. assoc. w/ receptor on target mem. - Rab-GTP can interact and bind to Rab effector - mem. need to fuse for cargo to be released into recipient compartment
43
question: how is vesicle fusion mediated?
- by mem. anchored prot. helices (SNARE prot.) - vesicle SNAREs (v-SNAREs) = anchored to vesicle mem. ⤷ ex. VAMP - target SNAREs (t-SNAREs) = anchored to target mem. ⤷ ex. syntaxin, SNAP25
44
explain: vesicle fusion (w/ SNAREs)
- SNARE complex forms + pulls mem. together - like a ball sitting on a sheet of paper - hole is created simultaneously through both allow mvt. of contents into target - OG mems. don't reseal, instead reseal together as 1 mem.
45
question: what makes up a SNARE complex?
- 4 helices - 2 from SNAP25 - 1 from syntaxin - 1 from VAMP **helices from target mem. and vesicle mem. weave together and pull mem. close
46
question: how is the SNARE complex disassembled and why?
- to reuse prot. - NSF and alpha-SNAP prot. assoc. w/ SNARE - unwinds helices
47
question: what is the purpose of retrograde movement?
- if prot. incorrectly brought to golgi from ER ⤷ ex. ER resident prot. - SNARE needs to be recycled to ER - COPII recep. need to be returned - unfolded prot. need to be returned ⤷ to be folded, modified, translocated out for degradation
48
question: how is a resident ER prot. recognized for retrograde?
- look for specific signal to get loaded onto COPI vesicles - KDEL seq. = lysine, aspartic acid, glutamine, leucine - lysine, lysine, xx - asparagine, x, glutamine
49
question: where is each signal for retrograde found?
- KDEL on soluble ER resident prot. - KKxx on resident ER mem. prot. - DxE on cargo acceptor from COPII vesicle

bio 2b03 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions