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Physiology > Cell Membrane, Membrane Transport, Etc. > Flashcards

Cell Membrane, Membrane Transport, Etc. Flashcards

1
Q

What are the functions of the plasma membrane?

A
  1. Separate cytoplasm from ECF
  2. Regulate exchange between ECF and Cytoplasm
  3. Communicate with other cells
  4. Provide structural attachments between cells or between cell and extracellular matrix
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2
Q

What is the structure of the plasma membrane?

A

Described by the Fluid Mosaic Model

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3
Q

What are the four molecules that make up the plasma membrane?

A

Phospholipids
Steroids
Proteins
Carbohydrates

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4
Q

What is the consistency of the plasma membrane at body temperature?

A

Thick oil

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5
Q

What is the structure of a phospholipid?

A

Amphipathic

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6
Q

How are phospholipids organized in a plasma membrane?

A

Bilayer

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7
Q

What are the functions of phospholipids in a plasma membrane?

A

Creates barrier

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8
Q

What can pass through a pure phospholipid bilayer?

A

Hydrophobic substances - Small, nonpolar molecules
Ex. (Gases (O2, CO2), Fatty acids, steroids
Lipophilic substances
Ex. Ethanol
Water

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9
Q

What cannot pass through a pure phospholipid bilayer?

A

Larger molecules
Polar molecules
Charged substances
Ex.
Glucose
Ions
Amino acids
Proteins

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10
Q

What is the purpose of cholesterol in a plasma membrane?

A

Help keep membrane fluid over a wide range of temperatures
Help to make membrane water tight

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11
Q

What determines the function of proteins?

A

Shape

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12
Q

What do mutations alter?

A

Primary structure

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13
Q

What does denaturation alter?

A

Secondary, tertiary, and quartenary structure

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14
Q

What can cause denaturation?

A

pH, T, Osm

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15
Q

What does Covalent/Allosteric Modular change?

A

Secondary, tertiary, and quartenary structure

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16
Q

What are the structural classifications of plasma membrane proteins?

A

Transmembrane
Integral
Peripheral

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17
Q

What do receptor proteins do?

A

Bind to specific chemical signals (ligands) and transmit that information to the cytoplasm

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18
Q

What are the properties of receptor proteins?

A

Specificity
Saturation
Competition

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19
Q

What is specificity of a receptor protein?

A

Shape of the binding site determines what will bind.
Each type of protein, in general, will interact with only one type of substance or class of substances

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20
Q

What is saturation of a receptor protein?

A

refers to the fraction of total binding sites that are occupied at any given time

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21
Q

What does saturation depend on?

A

on [protein] and the [substance]

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22
Q

Within solutions of the body there are a set number of what and a set number or what?

A

Proteins and binding sites

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23
Q

What is the transport rate proportional to?

A

Substrate concentration UNTIL carriers are saturated

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24
Q

What is a competitive inhibitor?

A

is a chemical substance (exogenous ligand) that binds to the active site of the protein and blocks the endogenous ligand from binding

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25
Q

When bound, what does a competitor do?

A

Does not produce an effect

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26
Q

What is level of inhibition depend on for a competitive inhibitor?

A

[protein], [endogenous ligand], and [competitive inhibitor].

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27
Q

Response of a cell to a chemical signal is mediated by what?

A

Receptor mediated, not signal mediated

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28
Q

What happens when one ligand binds to two different receptors?

A

Two different responses

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29
Q

What is receptor affinity?

A

Strength/Ease of ligand-receptor binding

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30
Q

Affinity is directly proportional to the number of ligands…

A

bound to receptors at any given [ligand]

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31
Q

If there is a high number of ligands bound to the receptor the affinity is…

A

high

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32
Q

Affinity is inversely proportional to…

A

Kd

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33
Q

What is Kd?

A

[Ligand] where ½ receptor occupied

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34
Q

What does Vm stand for?

A

Voltage to the membrane

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35
Q

What is membrane potential?

A

Charge difference across the plasma membrane

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36
Q

What creates the membrane potential?

A

unequal distribution of anions and cations across the cell membrane

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37
Q

What is the source of energy in a membrane potential?

A

Charge separation

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38
Q

What is resting membrane potential?

A

the charge difference across the plasma membrane when the cell is at rest.

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39
Q

What is a normal resting Vm?

A

≈ -70mV, depends on cell

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40
Q

What does the membrane potential create?

A

electrical gradients for movement of ions into/out of cells

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41
Q

What are some functions of the membrane potential?

A

Opens or closes gated ion channels.
Regulates exocytosis

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42
Q

COME BACK TO What is the electrochemical gradient?

A

Two gradients for the passive transport of charged substances across the membrane

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43
Q

What is the chemical gradient?

A

Ions will move passively down concentration gradients

44
Q

What is the electrical gradient?

A

Ions will move passively down electrical gradients

45
Q

What are the two gradients for the passive transport of charged substances across the membrane?

A

Chemical gradient and electrical gradient

46
Q

What does the strength of the electrical gradient depend on?

A

the valence of the ion and the magnitude of the membrane potential

47
Q

Is the larger gradient more of less powerful of drive for the opposite charge?

A

More/stronger; causes grated diffusion rate

48
Q

What happens if there is a divalent ion compared to a single valent ion?

A

Divalent has more of a diffusion drive

49
Q

What is equilibrium potential?

A

Vm that creates an ΔE that is equal in strength but opposite in direction of the ΔC

50
Q

What is the formula for equilibrium potential?

A

= 61/Z log ([ion]ECF / [ion]ICF)

51
Q

What is electrochemical equilibrium?

A

No net ion movement through channels via facilitated diffusion

52
Q

What is the equilibrium potential for potassium?

A

-94 mV

53
Q

What do transport proteins do?

A

Move hydrophilic substances across the plasma membrane of cell

54
Q

What are the 3 types of transport proteins?

A

Channels
Carriers
Active transporters

55
Q

What are channels?

A

Transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and Cytoplasm

56
Q

What is the function of channels?

A

Facilitated diffusion of ions into and out of cell (passive; does not require energy)

57
Q

Are channels specific?

A

Yes, somewhat

58
Q

What are the types of channels?

A

Open channels, gated channels

59
Q

What are open channels?

A

Always open and ions freely flow through via facilitated diffusion

60
Q

What do open channels create?

A

Leak currents

61
Q

What are gated channels?

A

Spend most of their time in the closed state, and will open only when stimulated

62
Q

What are the tree types of gated channels?

A

Chemically gated
Mechanically gated
Voltage gated

63
Q

What is allosteric modulation of gated channels?

A

Ligand-gated (ligand binds to open channel)

64
Q

What is covalent modulation of gated channels?

A

Kinase/phosphatase opening or closing channel

65
Q

What are carrier proteins?

A

Transmembrane protein that moves hydrophilic building blocks across the plasma membrane via facilitated diffusion

66
Q

What are the properties of carrier proteins?

A

Specificity
Saturation
Competition

67
Q

What are active transporters?

A

Transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane via active transport

68
Q

What are the properties of active transporters?

A

Specificity
Saturation
Competition

69
Q

What are structural proteins?

A

Forms cell to cell attachments that hold adjacent epithelial cells together

70
Q

What are tight junctions?

A

Prevents intercellular movement of fluid and dissolved substances

71
Q

What are the types of cell-to-cell junctions?

A

Tight junctions, desmosomes, gap junctions

72
Q

What are desmosomes?

A

Structural support

73
Q

What are gap junctions?

A

Cell to cell communication via ions

74
Q

What are enzymes?

A

Integral membrane, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell or inside cell

75
Q

What are the properties of enzymes?

A

Specificity
Saturation
Competition

76
Q

How long does it take for proteins to synthesize?

A

Approx. 2 hours

77
Q

Are proteins stored?

A

Yes, many synthesized in advance and stored in an inactive form, activated when needed

78
Q

What does storing proteins provide?

A

A means for immediate protein regulation

79
Q

What is the Mass Action Model?

A

P + S = PS; Interaction between substance and protein binding site follows this

80
Q

Where are carbohydrates on a plasma membrane?

A

Attached to EC surface of membrane lipids and proteins

81
Q

What do the carbohydrates on the plasma membrane form?

A

Glycocalyx

82
Q

What do carbohydrates do?

A

Plays important role in enabling cells to identify and interact with each other.

83
Q

Is sodium high inside or outside the cell?

A

Outside

84
Q

Is potassium high inside or outside the cell?

A

Inside

85
Q

Is calcium high inside or outside the cell?

A

Outside

86
Q

Is magnesium high inside or outside the cell?

A

Inside

87
Q

Is chloride high inside or outside the cell?

A

Outside

88
Q

Is bicarb high inside or outside the cell?

A

Outside

89
Q

Is phosphate high inside or outside the cell?

A

Inside

90
Q

Is glucose high inside or outside the cell?

A

Outside

91
Q

Are amino acids high inside or outside the cell?

A

Inside

92
Q

Is pH higher inside or outside the cell?

A

outside

93
Q

Are proteins high inside or outside the cell?

A

inside

94
Q

Does passive transport require energy?

A

No

95
Q

Does active transport require energy?

A

Yes

96
Q

What are the types of active transport?

A

Active transporters and bulk transport

97
Q

What are the types of passive transport?

A

Diffusion, osmosis, bulk flow

98
Q

What is random thermal motion?

A

Molecules in a fluid are continuously and randomly bouncing around

99
Q

What is the rate of movement proportional to?

A

Temperature divided mass

100
Q

What is diffusion?

A

Movement of substances other than water down a gradient

101
Q

When does the net movement of diffusion stop?

A

At equilibrium

102
Q

When does the random movement of diffusion stop?

A

Never

103
Q

Is diffusion substance specific?

A

Yes

104
Q

What is the primary goal of passive transport?

A

Moving the system towards equilibrium

105
Q

Does an concentration gradient increase or decrease net flux?

A

Increase

106
Q
A

Physiology (6 decks)

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