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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
What limits the amount of flux across the membrane of transporter proteins?
The fact that the molecule interacts/bonds with the transporter protein
26
Three factors determining the magnitude of solute flux in transporter proteins?
1. Saturation of transporter binding site (affinity and [solute]) 2. number of transporters 3. Rate of transport protein conformational change
27
Family of transporters for glucose
GLUT transpoters
28
Hormone that affects glucose transport in muscle and adipose tissue
Insulin
29
Using energy to move a substance uphill across a membrane
Active transport
30
Active transporters are often called _______
Pumps
31
______________ uses ATP to move substances against their electrochemical gradient
Primary active transport
32
_______________ uses energy stored in an electrochemical gradient to drive other solutes against their concentration gradeitn
Secondary active transport
33
___________ have a higher affinity facing one side of the membrane
Active transporters
34
_________ have the same affinity facing both sides of the membrane
Passive carriers
35
Mechanism of primary active transport
Hydrolysis of ATP changes the shape of a pump to move a solute across the membrane against its electrochemical gradient
36
Sodium-Potassium pump: hydrolysis of 1 ATP moves ___ number of ____ ions outwards and ___ number of ___ inwards
1 ATP moves 3 Na+ outside and 2 K+ inside
37
Phosphorylation of a primary active transporter causes...
A change in the affinity of the transporters binding site
38
ATPases are _______ ______ ________
Primary active transporter
39
Electrogenic pumps are ________ active transporters that _______ ___ and use the energy to transport ions across the membrane, resulting in a change in __________
primary; hydrolyze ATP; net charge across the membrane
40
Location of the Ca2+ pump
The plasma membrane and membrane of some organelles
41
Purpose of the Ca2+ pump
To maintain cytosolic [Ca2+]
42
________ active transport uses [ion] gradient across the membrane as an energy source
Secondary
43
Allosteric modulator
Substance that induces a conformational change upon binding, thereby changing the affinity of a protein for another molecule
44
Most common ion used to drive secondary active transport
Sodium
45
Cotransport of a solute via secondary active transport means....
Both molecules are transported into the cell
46
Countertransport of a solute via secondary active transport means....
The solute is being pumped out of the cell, as Na+ is pumped into the cell
47
Digitalis/digoxin is used for ______
People in heart failure to force muscle contraction
48
Mechanism of digitalis in heart muscle cells
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
Channels through which water can diffuse
Aquaporins
50
Water diffuses ______ H20 gradient and _______ solute gradient
Down; Up
51
_______ is a measure of the total number of dissolved particles per litre of solution
Osmolarity
52
If solution X is hyperosmotic to solution Y....
Solution X has a higher concentration of solutes
53
If solution X is hypoosmotic to solution Y....
Solution Y has a higher concentration of solutes
54
If solution X is isoosmotic to solution Y....
Solutions X and Y have the same concentration of solutes
55
An isotonic solution results in _____ flow of H20 from cell to solution and _____ in cell shape
No net flow; no change
56
A hypotonic solution results in _____ flow of H20 from cell to solution and _____ cell shape
Inward flow; swelling of cell and possible popping
57
A hypertonic solution results in _____ flow of H20 from cell to solution and _____ cell shape
Outward flow; shrinking of cell shape
58
A hypotonic solution has a higher osmolarity _______ the cell
inside
59
A hypertonic solution has a higher osmolarity ______ the cell
outside
60
Encapsulating particles from the extracellular fluid into vesicles is referred to as _______
Endocytosis
61
Expelling particles from vesicles into the extracellular fluid is referred to as _______
Exocytosis
62
When a ligand binds to a specific plasma membrane receptor and a vesicle forms (e.g. clathrin) then ________ is taking place
Receptor mediated endocytosis
63
When a cell engulfs a large solid particle such as a bacterium, then _______ is taking place
Phagocytosis
64
When tiny bits of extracellular fluid are taken up by a cell, then _____ is taking place
Bulk phase endocytosis
65
Pinocytosis is another word for ______
Buk phase endocytosis
66
After endocytosis, the vesicles then _____ --> ______ --> _____
Fuse with lysosomes (phagolysosome) --> sorting of contents --> distribution to various locations
67
_______ cells line hollow organs or tubes
Epithelial cells
68
The _________ membrane of epithelial cells faces a hollow or fluid-filled chamber
Luminal or apical
69
The ________ membrane of epitheliam cells is usually adjacent to blood vessels
Basolateral
70
The paracellular pathway of crossing epithelial cells includes...
Diffusion between adjacent cells of epithelium
71
The transcellular pathway of crossing epithelial cells includes...
Movement into an epithelial cell across either the luminal or basolateral membrane, diffusion through the cytosol, and exit across the opposite membrane
72
Transcytosis
Transport using vesicles to move a substance into, across, and out of a cell
73
A lethal hereditary disease where respiratory and other epithelial passages become clogged with thick mucous
Cystic fibrosis
74
Gene affected in cystic fibrosis
CFTCR
75
Mucous that thickens on luminal side of epithelial cells results from a defective pump that moves_____
Cl- out of cells into extracellular fluid

EPHE 242 (7 decks)

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