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EPHE 242 > Membrane Transport > Flashcards

Membrane Transport Flashcards

1
Q

Able to cross the membrane

A

Permeable

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2
Q

Not able to cross the membrane

A

Impermeable

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3
Q

The plasma membrane is ___ permeable

A

Selectively

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4
Q

Which types of molecules are the plasma membrane permeable to

A

Non-polar molecules (i.e. 02, CO2, steroids) and small uncharged polar molecules (i.e. H20, urea)
non-polar>small uncharged polar

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5
Q

Which types of molecules are the plasma membrane impermeable to

A

Ions (i.e. Na+, K+, Cl-) and large, uncharged, polar molecules (i.e. glucose)

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6
Q

A difference in the concentration of a chemical from one place to another (i.e. the inside vs outside of a plasma membrane)

A

Concentration gradient

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7
Q

A difference in electrical charges between two regions, such as across the plasma membrane

A

Electrical gradient

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8
Q

Both electrical and chemical forces acting on ions

A

Define electrochemical gradient

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9
Q

When a substance moves across the plasma membrane without any energy input from the cell, down the concentration or electrochemical gradient

A

Passive transport

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10
Q

When cellular energy, such as ATP, is used to move a substance across the plasma membrane, against the concentration or electrochemical gradient

A

Active transport

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11
Q

Three types of passive diffusion

A
  1. Simple diffusion
  2. Facilitated diffusion
  3. Osmosis
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12
Q

The random mixing of particles from one location to another because of the particles’ kinetic energy (energy of motion)

A

Diffusion

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13
Q

Diffusion time increases dramatically when you increase _______

A

Distance

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14
Q

The amount of material crossing a surface in a unit of time is called ______

A

Flux

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15
Q

Five factors influencing diffusion

A
  1. steepness of concentration gradient
  2. temperature
  3. Mass of the diffusing particle
  4. Surface area
  5. Diffusion distance
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16
Q 
Passive process in which
solutes move freely
through the lipid bilayer of
the plasma membranes of
cells without the help of
membrane transport
proteins
A

Simple diffusion

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17
Q

Two types of facilitated diffusion

A

Channel-mediated and carrier-mediated

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18
Q

Solute moves down its concentration or electrochemical gradient across the lipid bilayer through a membrane channel

A

Channel-mediated facilitated diffusion

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19
Q

Two types of channels

A

Open channels, and gated channels

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20
Q

Three ways that gated channel proteins are opened/closed

A
  1. Binding of molecules to channel proteins
  2. Changes in membrane potential
  3. Stretching the membrane
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21
Q

Three types of gated channel proteins

A
  1. Ligand gated
  2. Voltage-gated
  3. Mechanosensitive
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22
Q

________: method of facilitated diffusion that is used to move a solute down its gradient, but is not a continuous pore and the solute binds

A

Carrier mediated facilitated diffusion

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23
Q

Carrier that transports only one kind of molecule

A

Uniport carrier

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24
Q

Carrier that transports two or three kinds of molecules

A

Cotransporters

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25
Q

What limits the amount of flux across the membrane of transporter proteins?

A

The fact that the molecule interacts/bonds with the transporter protein

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26
Q

Three factors determining the magnitude of solute flux in transporter proteins?

A
  1. Saturation of transporter binding site (affinity and [solute])
  2. number of transporters
  3. Rate of transport protein conformational change
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27
Q

Family of transporters for glucose

A

GLUT transpoters

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28
Q

Hormone that affects glucose transport in muscle and adipose tissue

A

Insulin

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29
Q

Using energy to move a substance uphill across a membrane

A

Active transport

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30
Q

Active transporters are often called _______

A

Pumps

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31
Q

______________ uses ATP to move substances against their electrochemical gradient

A

Primary active transport

32
Q

_______________ uses energy stored in an electrochemical gradient to drive other solutes against their concentration gradeitn

A

Secondary active transport

33
Q

___________ have a higher affinity facing one side of the membrane

A

Active transporters

34
Q

_________ have the same affinity facing both sides of the membrane

A

Passive carriers

35
Q

Mechanism of primary active transport

A

Hydrolysis of ATP changes the shape of a pump to move a solute across the membrane against its electrochemical gradient

36
Q

Sodium-Potassium pump: hydrolysis of 1 ATP moves ___ number of ____ ions outwards and ___ number of ___ inwards

A

1 ATP moves 3 Na+ outside and 2 K+ inside

37
Q

Phosphorylation of a primary active transporter causes…

A

A change in the affinity of the transporters binding site

38
Q

ATPases are _______ ______ ________

A

Primary active transporter

39
Q

Electrogenic pumps are ________ active transporters that _______ ___ and use the energy to transport ions across the membrane, resulting in a change in __________

A

primary; hydrolyze ATP; net charge across the membrane

40
Q

Location of the Ca2+ pump

A

The plasma membrane and membrane of some organelles

41
Q

Purpose of the Ca2+ pump

A

To maintain cytosolic [Ca2+]

42
Q

________ active transport uses [ion] gradient across the membrane as an energy source

A

Secondary

43
Q

Allosteric modulator

A

Substance that induces a conformational change upon binding, thereby changing the affinity of a protein for another molecule

44
Q

Most common ion used to drive secondary active transport

A

Sodium

45
Q

Cotransport of a solute via secondary active transport means….

A

Both molecules are transported into the cell

46
Q

Countertransport of a solute via secondary active transport means….

A

The solute is being pumped out of the cell, as Na+ is pumped into the cell

47
Q

Digitalis/digoxin is used for ______

A

People in heart failure to force muscle contraction

48
Q

Mechanism of digitalis in heart muscle cells

A

Inhibits Na/K-pump sin heart muscle, which increases cytosolic [Na+], which decreases Na+ diffusion into the cell, which decreases Ca2+ exit from cell, which increases cytosolic [Ca2+], which increases force of contraction

49
Q

Channels through which water can diffuse

A

Aquaporins

50
Q

Water diffuses ______ H20 gradient and _______ solute gradient

A

Down; Up

51
Q

_______ is a measure of the total number of dissolved particles per litre of solution

A

Osmolarity

52
Q

If solution X is hyperosmotic to solution Y….

A

Solution X has a higher concentration of solutes

53
Q

If solution X is hypoosmotic to solution Y….

A

Solution Y has a higher concentration of solutes

54
Q

If solution X is isoosmotic to solution Y….

A

Solutions X and Y have the same concentration of solutes

55
Q

An isotonic solution results in _____ flow of H20 from cell to solution and _____ in cell shape

A

No net flow; no change

56
Q

A hypotonic solution results in _____ flow of H20 from cell to solution and _____ cell shape

A

Inward flow; swelling of cell and possible popping

57
Q

A hypertonic solution results in _____ flow of H20 from cell to solution and _____ cell shape

A

Outward flow; shrinking of cell shape

58
Q

A hypotonic solution has a higher osmolarity _______ the cell

A

inside

59
Q

A hypertonic solution has a higher osmolarity ______ the cell

A

outside

60
Q

Encapsulating particles from the extracellular fluid into vesicles is referred to as _______

A

Endocytosis

61
Q

Expelling particles from vesicles into the extracellular fluid is referred to as _______

A

Exocytosis

62
Q

When a ligand binds to a specific plasma membrane receptor and a vesicle forms (e.g. clathrin) then ________ is taking place

A

Receptor mediated endocytosis

63
Q

When a cell engulfs a large solid particle such as a bacterium, then _______ is taking place

A

Phagocytosis

64
Q

When tiny bits of extracellular fluid are taken up by a cell, then _____ is taking place

A

Bulk phase endocytosis

65
Q

Pinocytosis is another word for ______

A

Buk phase endocytosis

66
Q

After endocytosis, the vesicles then _____ –> ______ –> _____

A

Fuse with lysosomes (phagolysosome) –> sorting of contents –> distribution to various locations

67
Q

_______ cells line hollow organs or tubes

A

Epithelial cells

68
Q

The _________ membrane of epithelial cells faces a hollow or fluid-filled chamber

A

Luminal or apical

69
Q

The ________ membrane of epitheliam cells is usually adjacent to blood vessels

A

Basolateral

70
Q

The paracellular pathway of crossing epithelial cells includes…

A

Diffusion between adjacent cells of epithelium

71
Q

The transcellular pathway of crossing epithelial cells includes…

A

Movement into an epithelial cell across either the luminal or basolateral membrane, diffusion through the cytosol, and exit across the opposite membrane

72
Q

Transcytosis

A

Transport using vesicles to move a substance into, across, and out of a cell

73
Q

A lethal hereditary disease where respiratory and other epithelial passages become clogged with thick mucous

A

Cystic fibrosis

74
Q

Gene affected in cystic fibrosis

A

CFTCR

75
Q

Mucous that thickens on luminal side of epithelial cells results from a defective pump that moves_____

A

Cl- out of cells into extracellular fluid

EPHE 242 (7 decks)

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