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M2M Unit III > Membrane Structure > Flashcards

Membrane Structure Flashcards

1
Q

Membranes are composed of ____.

A

lipids, carbohydrates, and proteins

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2
Q

Membranes function as ____.

A

physical barriers that define boundaries

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3
Q

What controls the movement of molecules between the inside and the outside of the cell?

A

proteins

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4
Q

What forms the primary structure of the membrane?

A

lipids

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5
Q

______ are usually attached to the extracellular membrane surface.

A

Carbohydrates

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6
Q

All ______ are lipid bilayers with proteins embedded in or associated with the bilayer.

A

cell membranes

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7
Q

All cell membranes are ____ with _____ embedded in or associated with the bilayer.

A

lipid bilayers; proteins

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8
Q

____ of the all proteins encoded in the genome are membrane or membrane-associated proteins.

A

~30%

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9
Q

~30% of the all proteins encoded in the genome are _____.

A

membrane or membrane-associated proteins

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10
Q

Some signaling pathways depend on _____ or _____ of membrane lipids.

A

cleavage; phosphorylation

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11
Q

______ depends on composition and temperature.

A

Membrane fluidity

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12
Q

Membrane fluidity depends on _____ and ______.

A

composition; temperature

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13
Q

_____ catalyzes flip-flop using ATP.

A

Flippase

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14
Q

Flippase catalyzes ____ using ____.

A

flip-flop; ATP

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15
Q

_____ on membrane proteins and lipids are exceedingly important for development, immunological responses, binding of viruses and toxins, and for proper protein folding.

A

Carbohydrates

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16
Q

Carbohydrates on membrane proteins and lipids are exceedingly important for ______, ______, ______, and _____.

A

development, immunological responses, binding of viruses and toxins, and for proper protein folding.

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17
Q

All _____ are synthesized in the endoplasmic reticulum (ER).

A

membrane lipids

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18
Q

All membrane lipids are synthesized in the _____.

A

endoplasmic reticulum (ER)

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19
Q

The three classes of membrane lipids are _____, _____, and ______.

A

phospholipids, sphingolipids, and cholesterol

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20
Q

The most common phospholipids are

_____, ______, ______, and _____.

A

phosphatidylethanolamine (PE), phosphatidylcholine

PC), phosphatidylserine (PS), and phosphatidylinositol (PI

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21
Q

All lipid molecules are derived from _____ except for

_____, which is derived from sphingosine.

A

glycerol; sphingomyelin

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22
Q

All _____ are derived from glycerol except for

sphingomyelin, which is derived from _____.

A

lipid molecules; sphingosine

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23
Q

The ____ structure contains a polar hydroxyl group, a rigid steroid ring group, and a hydrocarbon tail

A

cholesterol

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24
Q

The cholesterol structure contains a ____, _____, and _____.

A

polar hydroxyl group, a rigid steroid ring group, a hydrocarbon tail

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25
Q

Cholesterol is intercalated among membrane _____.

A

phospholipids

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26
Q

The interaction of the cholesterol’s steroid ring with the hydrophobic tail of other phospholipids tends to ____ and _____.

A

immobilize the lipid; decrease fluidity

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27
Q

The interaction of the _____ with the _____ of other phospholipids tends to immobilize the lipid and decrease
fluidity.

A

steroid ring; hydrophobic tail

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28
Q

Lipids are forced to be straightened by ______.

A

cholesterol

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29
Q

_____ are forced to be straightened by cholesterol.

A

Lipids

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30
Q

The thickness of a membrane depends on _____.

A

the amount of cholesterol

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31
Q

The _____ depends on the amount of cholesterol.

A

thickness of a membrane

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32
Q

Intracellular membranes have ____ cholesterol than the plasma membranes and are ____ than the plasma membranes.

A

less; thinner

33
Q

_____ have less cholesterol and are thinner than

the _____.

A

Intracellular membranes; plasma membranes

34
Q

____ charged phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylinositol (PI) are more abundant on the internal surface.

A

Negatively

35
Q

Negatively charged _____, _____, and _____ are more abundant on the internal surface.

A

phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylinositol (PI)

36
Q

PC, sphingomyelin, and glycolipids are more abundant on the _____ surface.

A

external

37
Q

____, _____, and ____ are more abundant on the external surface.

A

PC, sphingomyelin, and glycolipids

38
Q

We get cholesterol from (1) ____ and (2) ____.

A

ingestion and uptake; synthesis by the liver

39
Q

Cholesterol uptake depends on _____.

A

the low density lipoprotein receptor (LDLR).

40
Q

There is ____ feedback for cholesterol production.

A

negative

41
Q

The first and rate-limiting enzyme in the cholesterol synthesis pathway is ____.

A

HMGCoA reductase (3-hydroxy-3-methylglutaryl coenzyme A reductase).

42
Q

Both cholesterol uptake and synthesis are regulated by the ____.

A

sterol regulatory element binding protein (SREBP)

43
Q

____, used to lower cholesterol, block the first (rate-limiting) step of cholesterol synthesis.

A

Statins

44
Q

Statins work on which step of cholesterol synthesis?

A

the first step- blocks HMGCoA reductase

45
Q

Both cholesterol ___ and ____ are regulated by the sterol regulatory element binding protein (SREBP)

A

uptake; synthesis

46
Q

____ is a protein containing a transcription factor that regulates both LDLR and all 30 of the synthesis proteins.

A

SREBP

47
Q

SREBP is a protein containing a transcription factor that regulates both ___ and ____.

A

LDLR; all 30 of the synthesis proteins

48
Q

If cholesterol is ___, the SREBP transcription factor is

released, moves to the nucleus, and activates all these genes.

A

low

49
Q

If cholesterol is low, the _____ is released, moves to the nucleus, and activates all these genes.

A

SREBP transcription factor

50
Q

The cholesterol level sensor is in the ____, where cholesterol is lowest in the cell and changes would be easiest to detect

A

ER membrane

51
Q

The cholesterol level sensor is in the ER membrane, where _____.

A

cholesterol is lowest in the cell and changes would be easiest to detect

52
Q

The proteases that cleave SREBP to release the bHLH are located in ____.

A

the Golgi complex

53
Q

SREBP must be held in ___ until cholesterol is low; then SREBP must move to ___ where it gets cleaved and the bHLH released.

A

the ER; the Golgi

54
Q

SCAP stands for?

A

SREBP cleavage activating protein

55
Q

____ binds both SREBP and sterols like cholesterol.

A

SCAP

56
Q

SCAP binds both ____ and _____.

A

SREBP; sterols like cholesterol

57
Q

Insig binds SCAP when _____ is high.

A

cholesterol

58
Q

Insig binds ____ when cholesterol is high.

A

SCAP

59
Q

____ binds SCAP when cholesterol is high.

A

Insig

60
Q

____, _____, and ____ are in complex when cholesterol is at normal levels.

A

SREBP, SCAP, Insig

61
Q

Insig binds SCAP only when cholesterol is ___.

A

high

62
Q

___ binds SCAP only when cholesterol is high.

A

Insig

63
Q

Insig binds ____ only when cholesterol is high.

A

SCAP

64
Q

When Insig binds SCAP, it blocks the ____.

A

SCAP signaling area.

65
Q

As cholesterol concentration drops, ___ no longer binds

____ and the complex gets packaged into vesicles to go to the ____.

A

Insig; SCAP; Golgi

66
Q

As cholesterol concentration ____, Insig no longer binds

SCAP and the _____ gets packaged into vesicles to go to the Golgi.

A

dropsSCAP/SREBP complex

67
Q

One cleavage that releases bHLH cuts SREBP in the ____.

A

transmembrane domain

68
Q

One cleavage that releases ___ cuts ____ in the transmembrane domain.

A

bHLH; SREBP

69
Q

The cleavage of bHLH from SREBP within the membrane is known as _____.

A

RIP, regulated intramembrane proteolysis.

70
Q

___ has been shown to be critical also for Notch signaling in development and for cleavage of the amyloid precursor protein (APP) to produce the bet amyloid peptide in Alzheimer’s disease.

A

RIP

71
Q

RIP has been shown to be critical also for _____
in development and for cleavage of the amyloid precursor protein (APP) to produce the beta
amyloid peptide in ____.

A

Notch signaling; Alzheimer’s disease

72
Q

When LDL cholesterol levels are less than 100 mg/dl (total plasma cholesterol of 170 mg/dl), heart attacks are ____.

A

rare

73
Q

When ____ cholesterol levels are less than ___ mg/dl (total plasma cholesterol of 170 mg/dl), heart attacks are rare.

A

LDL; 100

74
Q

Of the roughly 22,000 genes in the human genome, about ____ encode membrane transport proteins and ion channels.

A

one-tenth (2200)

75
Q

Of the roughly 22,000 genes in the human genome, about one-tenth (2200) encode ____.

A

membrane transport proteins and ion channels

76
Q

A variety of proteins are anchored to the membrane by ____.

A

glycosylphosphatidylinositol

77
Q

Glycosylphosphatidylinositol’s function?

A

anchors proteins to the membrane

78
Q

____ is found only on the exoplasmic/extracellular face.

A

Glycosylphosphatidylinositol

79
Q

Glycosylphosphatidylinositol is found only on the ____.

A

exoplasmic/extracellular face

M2M Unit III (30 decks)

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