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Cell Bio > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

Membranes act as

A

Permeability barriers

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2
Q

All cells have a

A

Plasma membrane

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3
Q

have internal membranes that enclose intracellular compartments (e.g., organelles and vesicles)

A

Eukaryotes

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4
Q

Membrane functions are

A

Receive info from environment, selective import and export, enable cells to change shape, expand

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5
Q

The membrane is a

A

thin bilayer + proteins

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6
Q

Carbohydrates are located on the

A

ECF surface of membrane

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7
Q

Membrane proteins float in a

A

sea of lipids

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8
Q

how thick is the plasma membrane

A

5 nm thick

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9
Q

Membrane lipids __ form bilayers in water

A

spontaneously

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10
Q

The lipid bilayer is a __ dimensional fluid

A

2

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11
Q

The fluidity of a lipid bilayer depends on its

A

composition

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12
Q

The lipid bilayer is asymmetrical or symmetrical

A

asymmetrical

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13
Q

Lipid asymmetry is preserved during

A

membrane transport

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14
Q

Membrane lipids have __ head group and __ hydrocarbon tails

A

polar, one or two (hydrophobic)

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15
Q

Membrane lipids form a bilayer in

A

water

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16
Q

Geometry of membrane lipids favors

A

bilayer formation

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17
Q

Phospholipid bilayers __ form sealed compartments

A

spontaneously

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18
Q

Holes in membranes are __ to minimize interactions of hydrophobic molecules with water

A

rapidly resealed

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19
Q

Membrane lipids move rapidly within one

A

monolayer

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20
Q

The most abundant lipids in cell membranes are

A

phospholipids

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21
Q

have a phosphate-containing polar head group

A

phospholipid

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22
Q

the most abundant phospholipid

A

Phosphatidylcholine

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23
Q

what determines membrane fluidity

A

length and saturation of hydrocarbon tails

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24
Q

__ tails promote membrane fluidity

A

short

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25
Q

Double bonds introduce kinks and __ membrane fluidity

A

increase

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26
Q

Special membrane lipid

A

cholesterol

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27
Q

Cholesterol characteristics

A

Rigid sterol ring with a polar head group & one
short hydrocarbon tail

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28
Q

can fill the spaces between neighboring phospholipid
molecules produced by the kinks in their tails

A

cholesterol

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29
Q

Tends to stiffen membranes with unsaturated tails

A

cholesterol

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30
Q

phospholipids have what charge

A

negative

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31
Q

Increasing the number of double bonds in lipid tails does what to fluidity

A

increases

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32
Q

Shortening the length of lipid hydrocarbon tails does what to fluidity

A

increases

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33
Q

saturated fats have long or short tails

A

short

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34
Q

Moving veggie oil from room temp to fridge does what to the fluidity

A

decreases

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35
Q

Glycolipids have

A

carbs on their heads

36
Q

T or F the two monolayers have the same lipids

A

false, different

37
Q

Lipids are __ arranged between two monolayers

A

asymmetrically

38
Q

New phospholipids are synthesized
by

A

enzymes bound to cytosolic surface of the ER

39
Q

Enzymes that synthesize phospholipids insert the new lipids into the

A

cytosolic monolayer of the ER membrane

40
Q

randomly transfer lipids to the lumenal (or extracellular) monolayer

A

Scramblases in the ER

41
Q

Membrane bilayers move from

A

ER to Golgi

42
Q

selectively transfer some lipids from the monolayer that faces the lumen to the cytosolic monolayer

A

flippases in golgi

43
Q

flippases in golgi generate an

A

asymmetric distribution of membrane lipdis

44
Q

Asymmetry is maintained during

A

transport and after

45
Q

becomes the
extracellular surface of the
plasma membrane

A

lumenal surface

46
Q

Enables membranes to
maintain the asymmetric
distribution of lipids, proteins,
and carbohydrates

A

lumenal surface

47
Q

The cytosolic surface is

A

outside

48
Q

The c terminal end is always in the

A

cytosolic surface

49
Q

provides the barrier function,
membrane proteins provide other functions

A

lipid bilayer

50
Q

Proteins (membrane spanning polypeptide chains) usually cross membranes as an

A

alpha helix

51
Q

Membrane proteins can be purified using

A

detergents

52
Q

The plasma membrane is often reinforced by the

A

cell cortex

53
Q

proteins that are directly attached to the membrane

A

Integral membrane

54
Q

Transmembrane, monolayer-associated, lipid-linked

A

integral membrane proteins

55
Q

Can only be removed from the membrane using detergents

A

integral membrane proteins

56
Q

Non-covalent association with other membrane proteins

A

peripheral membrane proteins

57
Q

Can be released from the membrane with gentle procedures (e.g. salt)

A

peripheral membrane proteins

58
Q

what protein is easier to seperate

A

peripheral membrane proteins

59
Q

__ amino acids
form an alpha-helix

A

20 hydrophobic

60
Q

Polar atoms of the polypeptide
backbone are

A

hydrogen bonded
inside the alpha-helix

61
Q

Hydrophobic amino acid side
chains on the surface of the
helix interact with

A

lipid tails

62
Q

Multiple a-helices can pack together to form an

A

aqueous pore

63
Q

Several __
alpha-helices cross
the lipid bilayer

A

amphipathic

64
Q

_ surfaces (green) contact the
bilayer

A

hydrophobic

65
Q

_ surfaces (red) form an aqueous pore

A

hydrophilic

66
Q

Some transmembrane proteins use several
__ to cross the membrane

A

beta sheets

67
Q

e “beta barrels” form

A

large pores

68
Q

detergents contain

A

hydrophobic regions that solubilize lipid bilayer and hydrophilic regions

69
Q

SDS will __ proteins

A

denature

70
Q

Detergents have __ hydrophobic tail, so they
form __ rather than bilayers

A

1, micelles

71
Q

How to measure membrane protein movement?

A

Fluorescence Recovery After Photobleaching (FRAP)

72
Q

Look at the behavior of many molecules; Time for recovery reflects the mobility of the molecules

A

FRAP

73
Q

Look at the behavior of only a few labeled molecules; Distance traveled reflects mobility of molecule

A

SPT

74
Q

The cells can restrict membrane protein mobility by tethering to

A

cytoskeleton, extracellular matrix, membrane proteins in another cell, and form junctions to create domains

75
Q

Distinct membrane domains are common in

A

epithelial cells

76
Q

mediates transport of nutrients from the gut into the cell

A

Protein A (apical side)

77
Q

mediates transport of solutes from the cell into the bloodstream

A

Protein B (basal side)

78
Q

form a belt that keeps A and B from mixing

A

tight junctions

79
Q

The plasma membrane is reinforced by
interactions with the

A

cell cortex

80
Q

good model for studying membrane cortex interactions

A

red blood cells

81
Q

Major fibrous protein is

A

spectrin

82
Q

spectrin is attached to

A

transmembrane proteins

83
Q

Forms a mesh that protects RBC from mechanical damage

A

spectrin

84
Q

recognize specific
oligosaccharides on a neutrophil

A

lectins on endothelial cells

85
Q

lectins facilitate

A

attachment to blood vessel wall

Cell Bio (15 decks)

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