Brainscape's Knowledge GenomeTM

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


See full index

Adv Cell Bio Quiz 02 > Lec 08: Membrane Proteins and Transport > Flashcards

Lec 08: Membrane Proteins and Transport Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What are some ways membrane proteins can associate with other membranes? (Figure 10-17)

A
  1. Integral/transmembrane proteins 2. Peripheral membrane proteins 3. Lipid anchored membrane proteins 4. Membrane associated proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Polypeptide chain of transmembrane proteins

A

often cross membrane as a-helix

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

Cytosolic side chains of transmembrane polypeptide

A

-non-polar: gly, phe, leu, ala, thr (cytosol) -polar: his

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

extracellular space side chains of transmembrane polypeptide

A

-non-polar: ile, ala, cys, gly, phe, ala -polar: his, ser, tyr

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

Polarity of peptide bonds in transmembrane proteins

A

polar (number of hydrogen bonds are maximized in a-helix)

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

How can transmembrane helices be predicted?

A

amino acid sequence (hydropathy plot)

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

Mechanism of membrane spanning helices

A

-helix bending = loss of hydrogen-bonds ((exception: helices don’t contact lipids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Transmembrane B-barrel

A

-proteiens crystallize readily -relatively rigid

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

Lipid anchors mediate?

A

Lipid anchors (fatty acid chain) mediate membrane association of some proteins

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

3 lipid anchors

A
  1. myristoyl 2. palmitoyl 3. farnesyl
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

myristoyl anchor

A

amide linkage between terminal amino group and myristic acid

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

palmitoyl anchor

A

thioester linkage between cystein and palmitic group

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

farnesyl anchor

A

-prenyl chain thioether linkage between cysteine and prenyl group

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

The membrane association of many signaling proteins is controlled by?

A

lipid anchors

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

Src family kinases lipid anchors

A

-are myristoylated → This anchor alone mediates only weak membrane association → Kinase activation results in addition of a palmitic acid to cysteine

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

Rab GTPases (lipid anchors)

A

-lipidated -C-terminal cysteines are modified with 1-2 geranylgeranyl anchors → Anchors are displayed in GTP-bound, but not GDP-bound state

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

How are Extracellular moieties of proteins modified?

A

→ Glycosylated → Formation of disulfide bridges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do glycosylated extracellular moieties of proteins modified?

A

highly varied sugar modifications that mediate specific cell-cell interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

glycocalyx formed by?

A
  • Glycosylated lipids and proteins (glycoproteins and proteoglycans) - Adsorbed glycoproteins (compounds of extracellular matrix)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

glycocalyx function

A

-protect against mechanical/chemical insults (low pH, digestive enzymes) -prevents unappropriated cell-cell interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How do membrane proteins move?

A

-directional (coupled to active process) -diffusion (rotational/ lateral)

22
Q

Membrane proteins can be

A

• pack in crystal-like aggregates • confined by intercellular integrations

23
Q

Membrane proteins and lipids confined to?

A
  • apical and basolateral domains
  • lipid rafts
  • by interactions - extracellular (e.g. matrix) - intracellular (e.g. with cytoskeleton)
24
Q

cortical cytoskeleton

A

-reinforces the plasma membrane mechanically (genetic abnormalities in spectrin cause anemia) → restricts diffusion of membrane molecules

25
Q

cortical cytoskeleton is rich in ?

A

actin

26
Q

dynamic remodeling of actin in cortical cytoskeleton

A

→ cell motility → endocytosis → transient membrane structures (e.g. filopodia)

27
Q

How does cortical cytoskeleton restrict diffusion of membrane molecules?

A

closely apposed to plasma membrane → restricts molecule motion (transiently or permanently) → plasma membrane is divided into corrals, that function by concentration proteins, such as signaling proteins

28
Q

How is cell membrane shape established and maintained?

A

→ pushing and pulling forces → membrane-bending proteins → Clustering of particular lipids - Phoshoinosides - Lipids subjected to phospholipase

29
Q

Membrane-bending proteins

A

→ that insert hydrophobic moiety only in one membrane leaflet → proteins that bind to membrane (Example: Clathrin coat) -lipid anchor

30
Q

How do membrane-bending proteins insert hydrophobic moiety only in one membrane leaflet?

A

hydrophobic protein domain (Example: Reticulons in ER tubule)

31
Q

Membrane transport proteins

A

→ are abundant → are multi-pass transmembrane proteins → are specific

32
Q

2 classes of membrane transport proteins

A

1) transporters 2) channels

33
Q

2 types of membrane transporters

A

-carriers -permeases

34
Q

Direction of diffusion determined by?

A

electrochemical gradient

35
Q

Diffusion direction of uncharged solutes determined by?

A

concentration gradient

36
Q

Diffusion direction of solutes with net charge determined by?

A
  1. concentration gradient 2. electrical gradient
37
Q

Rate of transporter-mediates vs channel-mediated diffusion (chart)

A

Channel–> up to 10^8 molecules/second Transporter–> 10^2-10^4 molecules/second

38
Q

Rate of transporter-mediates vs channel-mediated diffusion (chart)

A

Channel–> up to 10^8 molecules/second Transporter–> 10^2-10^4 molecules/second

39
Q

Transporters have a?

A

-Vmax -Km -can be inhibited (competitive or allosteric inhibition)

40
Q

Vmax

A

speed of conformational change

41
Q

Km

A

affinity for substrate

42
Q

Active membrane transport

A

powers transport of a molecule against the electrochemical gradient

43
Q

Three types of active membrane transport (figure)

A
  • uniporter - symporter - antiporter
44
Q

Coupled transporter

A

-use electrochemical gradient of one molecule to pump another molecule -drives secondary active transport -works backwards like an enzyme

45
Q

Na+ symporters functionality

A

-cooperative binding -conformational change only possible when completely empty or fully occupied -thermal energy drives conformational change

46
Q

Na+ symporters

A
  • transport molecules such as sugars, amino acids, and neurotransmitters - are abundantly expressed in intestine, kidney, and neurons
47
Q

Transporters are built from?

A

inverted repeats/functional symmetry due to pseudosymmetric conserved core generated by gene duplication

48
Q

transcellular transport enabled by?

A

asymmetric distribution of transporters across apical/basolateral membrane domains

49
Q

Microvilli can ?

A

increase absorptive membrane area up to 25 fold

50
Q

Tight junction function

A

permeability barrier for solutes and membrane proteins

Adv Cell Bio Quiz 02 (5 decks)

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