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BIO108 - General Physiology > Lecture 2.2 - Membranes, Channels and Transport > Flashcards

Lecture 2.2 - Membranes, Channels and Transport Flashcards

1
Q
  • diffusion of water across a selectively permeable embrane
  • continues until the solutions are isotonic
A

osmosis

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2
Q

osmosis continues until the solution are __

A

isotonic

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3
Q

in osmosis, water moves from __ to __ water potential

A

higher to lower

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4
Q

the movement of water can produce a __ __, resulting in a pressure gradient across a semipermeable membrane

A

hydrostatic pressure

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5
Q

hydrostatic pressure is a __ __ pressure

A

fluid mechanical pressure

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6
Q

the difference in hydraulic pressure of a solution and water which must be overcome to prevent the entry of water into the solution across the membrane

A

osmotic pressure

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7
Q

osmotic pressure is described by __ equation

A

Van t’Hoff

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8
Q

when two aqueous solutions exert the same osmotic pressure through a membrne permeable only to water

A

isosmotic

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9
Q

if one solution exerts less osmotic pressure than the other

A

hypoosmotic

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10
Q

if one solution exerts greater osmotic pressure than the other

A

hyperosmotic

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11
Q

the concentration of a solution expressed as the total number of solute particles per liter

A

osmolarity

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12
Q

response of cells or tissues immersed in the solution

A

tonicity

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13
Q

osmotic pressure property of a solution

A

osmoticity

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14
Q
  • no osmotic pressure difference between the cell and interior and the extracellular solution
  • no net water gain
  • cell/tissue neither shrinks nor swell
A

isotonic solution

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15
Q

solution causes swelling of tissue

A

hypotonic solution

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16
Q

solution causes shrinking of tissue

A

hypertonic solution

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17
Q

what happens to the cell in a very hypotonic solution

A
  • lysis (animal cell)
  • turgid (plant cell)
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18
Q

what happens to the cell in an isotonic solution

A
  • normal (animal cell)
  • flaccid (plant cell)
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19
Q

what happens to the cell in a very hypertonic solution

A
  • shriveled (animal cell)
  • plasmolyzed (plant cell)
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20
Q

hydrostatic pressure that puts cell walls in tension

A

turgor pressure

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21
Q

fatty acid tail in soap bubble

A

pointing out

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22
Q

fatty acid tail in lipid vesicle

A

pointing in

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23
Q

transport proteins tend to be __ for one molecule, so substances can only corss a membrane if it contains the appropriate protein

A

specific

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24
Q

Two kinds of transport proteins

A
  • channel
  • carrier
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25
Q

allows charged substances (usually ions) to diffuse across membranes

A

water-filled pore or channel

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26
Q

most channels can be __, allowing the cell to control the entry and exit of ions

A

gated

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27
Q

small organic compounds that specifically transport ions across the plasma membrane

A

ionophores

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28
Q

open or closes gated chanels

A

physical or chemical stimulus

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29
Q

transports a single solute from one side of the membrane to the other

A

uniporters

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30
Q

transfer one solute and simultaneously or sequentially transfer a second solute

A

coupled transporters

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31
Q

two types of coupled transporters

A
  1. symporters
  2. antiporters
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32
Q

transfer solutes in the same direction

A

symporters

33
Q

transfer solutes in opposite directions

A

antiporters

34
Q

show saturation kinetics

A

channel and carrier-mediated transport mechanisms

35
Q

binding site for a specific solute and constantly flip between two states so that the site is alternately open to opposite sides of the membrane

A

diffusion through carrier

36
Q

in diffusion through carrier, the substance will bind on the side with __ concentration and be released at __ concentration side

A

higher, lower

37
Q

require metabolic energy and moves substances against their gradients

A

active transports

38
Q

supplies the energy for most active transport

A

ATP

39
Q

actively maintains the gradient of sodium (Na+) and potassium (K+) across the membrane

A

sodium-potassium pump

40
Q

ratio of sodium to potassium

A

3 Na+ out of cell
2 K+ into cell

41
Q

sodium is transported (interior to exterior) against a __ concentration gradient

A

10:1

42
Q

net flux of charge in sodium-potassium pump

A

one positive charge
(3 Na+ - 2K+)

43
Q

membrane protein couples the transport of two solutes

A

cotransport

44
Q

cotransport with __ renders substrate transport against its concentration gradient energetically favorable

A

Na+

45
Q

run on energy stores in ion gradients

A

symporters

46
Q
  • Na+/H+ in the proximal tubule of mammalian kidney
  • for each H+ expelled, one Na+ is taken up into the cel
  • avoids expenditure of energy to perform electrical work
A

antiporters

47
Q

Summary of Membrane Transport:
Uses energy

A
  1. Lipid diffusion - N
  2. Osmosis - N
  3. Passive Transport - N
  4. Active Transport - Y
48
Q

Summary of Membrane Transport:
Uses proteins

A
  1. Lipid diffusion - N
  2. Osmosis - N
  3. Passive Transport - Y
  4. Active Transport - Y
49
Q

Summary of Membrane Transport:
Specific

A
  1. Lipid diffusion - N
  2. Osmosis - Y
  3. Passive Transport - Y
  4. Active Transport - Y
50
Q

Summary of Membrane Transport:
Controllable

A
  1. Lipid diffusion - N
  2. Osmosis - N
  3. Passive Transport - Y
  4. Active Transport - Y
51
Q

how do small molecules and water enter or leave the cell

A

through lipid bilayer or by transport proteins

52
Q

how do large molecules, such as polysaccharides and proteins, cross the membrane

A

via vesicles

53
Q

Two types of movement of large molecules across membranes

A
  1. endocytosis
  2. exocytosis
54
Q

cell brings in macromolecules and particulate matter by forming new vesicles from the plasma membrane

A

endocytosis

55
Q

Types of endocytosis

A
  1. pinocytosis
  2. phagocytosis
  3. receptor-mediated endocytosis
56
Q
  • cell creates a vesicle around a droplet of extracellular fluid
  • cellular drinking
  • non-specific process
A

pinocytosis

57
Q
  • cellular eating
  • ingesting and eliminating particles larger than 0.5 μm in diameter
A

phagocytosis

58
Q
  • depends on the presence of receptor molecules embedded in the cell membrane
  • triggered when extracellular substances bind to special receptors, ligands, on the membrane surface, especially near coated pits
A

receptor-mediated endocytosis

59
Q
  • molecules that bind to receptors and cause changes in cell signaling
  • can be intracellular or extracellular
A

Ligands

60
Q

transport proteins from organelle to organelle

A

clathrin- coated vesicles

61
Q

when vesicle and plasma membrane come in contact, the bilayers fuse and spill the contents to the outside

A

exocytosis

62
Q

Three main types of intercellular links

A
  1. tight junctions
  2. adhering junctions (zonula adherens, desmosomes)
  3. gap junctions
63
Q
  • membranes of adjacent cells are fused, forming continuous belts around cells
  • prevent leakage of extracellular fluid across a layer of epithelial cells
A

tight junctions

64
Q
  • fasten cells together intro strong sheets, much like rivets
  • reinforced by intermediate filaments of keratin
  • attach muscle cells to each other in a muscle
A

desmosome (anchoring junctions)

65
Q
  • provide cytoplasmic channels between adjacent cells
  • salt ions, sugar, amino acids, and other small molecules can pass
A

gap junction (communicating junctions)

66
Q

every cell maintains concentrations of inorganic solutes inside the cell that are different from those outside the cell

A

ionic steady state

67
Q

Two ways to prevent osmotic swelling in cells

A
  1. pump water out as fast as it leaks in
  2. pump out solutes that leak into the cell
68
Q

major mechanism for regulation of cell volume

A

pump out solutes that leak into the cell

69
Q

Where do membrane permeability to charged particles depend on

A
  1. membrane permeability constant
  2. electrical signal
70
Q

Two forces that act on charged atoms and molecules to produce a net passive diffusion

A
  1. chemical gradient
  2. electric field
71
Q

arising from differences in the concentration of the substance on the two sides of the membrane

A

chemical gradient

72
Q

difference in electrical potential across the membrane

A

electric field

73
Q

where will an ion move away from

A

regions of high concentration

74
Q

where will an ion move toward

A

increasing negative potential (if it is a cation)

75
Q

determined by the sum of the combined forces of the concentration gradient and electrical gradient

A

electrochemical gradient

76
Q

potential at which an ion is in electrochemical equilibrium

A

equilibrium potential

77
Q

how can an ion species passively diffuse AGAINST its chemical concentration gradient

A

if electrical gradient across the membrane is in the opposite direction and exceeds the concentration gradient

78
Q

will not be affected by electrical forces but by the concentration gradient

A

uncharged molecules (sugar)

79
Q
  • results in an unequal distribution of diffusible ions across the membrane.
  • Despite the unequal distribution, the solutions on both sides of the membrane remain electrically neutral.
A

Donnan equilibrium

BIO108 - General Physiology (9 decks)

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