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ZZZ - BIO108 - General Physiology > Lecture 2.1 - Membranes, Channels and Transport > Flashcards

Lecture 2.1 - Membranes, Channels and Transport Flashcards

1
Q
  • separates the cytoplasm from the external environment
  • one of the most important cell organelles
  • highly selective permeable barrier that surrounds all living cells
  • controls how molecules and compounds move in and out of the cell
  • important for proper nutrition, maintenance of irritability of the cells, and homeostasis
A

cell membrane

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2
Q

cell membranes are __ __ __ barrier

A

highly selective permeable

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3
Q

cell membranes controls how molecules and compounds move ___ of cell

A

in and out

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4
Q

importance of cell membrane

A
  1. proper nutrition
  2. maintenance of irritability
  3. homeostasis
  4. signal detection
  5. cell-to-cell communication
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5
Q

for organization and localization of specific functions

A

compartmentalization

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6
Q

thickness of cell membrane

A

6-23 nm

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7
Q

what happens when the cell membrane sustains different concentrations of certain ions on their two sides

A

lead to concentration gradient

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8
Q

participates in the transport of substances

A

protein structures

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9
Q
  • model that describes the organization of cell membranes
  • phospholipids drift and move like a fluid
  • bilayer is a mosaic mixture of phospholipids, steroids, proteins, and other molecules
A

fluid mosaic model

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10
Q

membrane composition

A
  1. phospholipids
  2. proteins
  3. carbohydrates
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11
Q

how are lipids and protein molecules in the cell membrane kept together

A

non-covalent interactions

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12
Q

impermeable to the passage of most water-soluble molecules

A

lipid bilayer

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13
Q

fundamental structure of the membrane

A

lipid molecules

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14
Q
  • usually span from one side of the phospholipid bilayer to the other, but can also sit on one of the surfaces
  • can slide around the membrane very quickly and collide with each other, but selfom flip from one side to the other
  • responsible for most of the membrane’s properties
A

proteins

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15
Q

Two types of proteins based on where they are found

A
  1. integral proteins
  2. peripheral proteins
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16
Q
  • embedded in the lipid bilayer
  • provide a mechanism for trans-membrane transport
A

integral proteins

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17
Q

different trans-membrane transport integral proteins provide a mechanism for

A
  1. passive transport pores and channels
  2. active transport pumps and carriers
  3. membrane-linked enzymes
  4. chemical signal receptors and transducers
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18
Q

associated with the surface of the membrane via electrostatic interaction

A

peripheral proteins

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19
Q

how are the peripheral proteins associated with the surface of the membrane

A

via electrostatic interaction

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20
Q

what do proteins inside the surface maintain

A

cell shape or cell motility

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21
Q

catalyze reactions in the cytoplasm

A

enzymes

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22
Q

what are receptor proteins used for

A
  • cell signaling
  • cell recognition
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23
Q

Different major cell functions of the proteins in plasma membrane

A
  1. transport
  2. enzymatic activity
  3. signal transduction
  4. intercellular joining
  5. cell-cell recognition
  6. attachment to the cytoskeleton and extracellular matrix (ECM)
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24
Q

Special functions of proteins

A
  1. adhesion proteins
  2. recognition proteins
  3. receptor proteins
  4. enzymes
  5. transport proteins (active and passive)
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25
Q
  • found on the outer surface and attached to the proteins or sometimes to the phospholipids
  • form a cell coat outside the cell membrane
A

carbohydrates

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26
Q

Different types of carbohydrates on the cell membrane

A
  1. glycoproteins
  2. glycolipids
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27
Q

carbohydrate chains attached to membrane proteins

A

glycoproteins

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28
Q

carbohydrate chains attached to the lipid element of the cell membrane

A

glycolipids

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29
Q
  • defined as a thick mixture of protein lipids and post-translational sugar structures
  • surround all living cells and act as a buffer
A

Glycocalyx

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30
Q

functiono of glycocalyx

A
  • protection
  • cell recognition
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31
Q

facilitate cellular recognition

A

glycolipid

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32
Q

serve as receptor for chemical signals

A

glycoproteins

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33
Q

what is the side chain of glycoproteins

A

oligosaccharide side chain

34
Q

Primary types of lipids

A
  1. phosphoglycerides
  2. sphingolipids
  3. sterols
35
Q

glycerol backbone

A

phosphoglycerides

36
Q

backbone made of sphingosine bases

A

sphingolipids

37
Q

cholesterol, nonpolar and only slightly soluble in water

38
Q

amphipathic lipids

A
  • phosphoglycerides
  • sphingolipids
39
Q

what does the differences in the lengths of the two fatty acid tails and composition influence

40
Q

binds weakly to phospholipids making the membrane less fluid but stronger

A

cholesterol

41
Q

how are membrane molecules help in place

A

relatively weak hydrophobic interactions

42
Q

Two possible movement of phospholipids

A
  1. lateral movement
  2. flip-flop
43
Q

frequent movement of phospholipids

A

lateral movement

44
Q

rare movement of phospholipids

45
Q

influenced by temperature and constituents

A

membrane fluidity

46
Q

what influences membrane fluidity

A

temperature and constituents

47
Q

fluid membrane

A

unsaturated hydrocarbon tails with kinks

48
Q

viscous membrane

A

saturated hydrocarbon tails

49
Q
  • wedged between phospholipid molecules in the plasma membrane of animal cells
  • at warm temperature, it restrains the movement of phospholipids and reduces fluidity
  • at cool temperatures, it maintains fluidity by preventing tight packing
A

steroid cholesterol

50
Q

what does steroid cholesterol do at warm temperatures

A

restrains movement of phospholipids and reduce fluidity

51
Q

what does steroid cholesterol do at cool temperatures

A

maintains fluidity by preventing tight packing

52
Q

enzymes that break down protein

A

Proteolytic enzymes (proteases)

53
Q
  • consists of physically breaking apart (fracturing) a frozen biological sample
  • used to split the cell membrane apart
A

freeze-fracture technique

54
Q

what was seen when a cell membrane was freeze fractured

A

protein particles interspersed with a smooth matrix, supporting fluid mosaic model

55
Q
  • rate at which a substance can passively penetrate a cell membrane
  • influenced by inherent properties of both the membrane and the substance
A

membrane permeability

56
Q

Different Transport Systems

A
  1. passive process
  2. active transport (pumping)
57
Q
  • no energy expenditure and move down their normal gradient
  • simple diffusion/lipid diffusion
  • osmosis
  • facilitated diffusion
A

passive processes

58
Q
  • requires metabolic energy
  • moves substances against their gradients
A

active transport (pumping)

59
Q

Different types of passive transport

A
  1. simple diffusion/lipid diffusion
  2. osmosis
  3. facilitated diffusion/passive transport
60
Q

Three basic routes in transport systems

A
  1. dissolving in lipid phase
  2. diffusion through labile or fixed aqueous channels
  3. carrier-mediated transport
61
Q
  • dissolves directly in the lipid bilayer
  • enters the aqueous phase on the opposite side
A

dissolving in the lipid phase

62
Q
  • solute molecule remains in the aqueous phase
  • diffuses through aqueous channels (water-filled pores in the membrane)
A

diffusion through labile or fixed aqueous channels

63
Q

water-filled pores in the membrane

A

aqueous channels

64
Q
  • solute molecule combines with a carrier molecule dissolved in a membrane
  • carrier “mediates” of “facilitates” the movement of the solute molecule across the membrane
A

carrier-mediated transport

65
Q

random thermal motion of suspended or dissolved molecules causes their dispersion from regions of higher concentration to regions of lower concentrations

66
Q

each substance diffuse down its __ concentration gradient, independent of the concentration gradies of other substances

67
Q

diffusion of a substance across a biologial membrane

A

passive transport

68
Q

Diffusion is __ because in this process the particle uses free energy (potential energy).

69
Q

states that the rate of diffusion across a membrane is directly proportional to the concentration gradient of the substance on the two sides of the membrane and inversely related to the thickness of the membrane

A

Fick’s Law of Diffusion

70
Q

According to Fick’s Law, diffusion is proportional to what?

A
  • concentration gradient
  • difference in partial pressure
71
Q

intrinsic factors governing diffusion across membranes

A
  1. size rules
  2. polarity rules
  3. ionic rules
72
Q

size rule ex.

A

water > urea

73
Q

polarity rule ex.

A

non polar > polar

74
Q

ionic rule ex.

75
Q

Five factors where the rate of diffusion depends on

A
  1. size
  2. temperature
  3. steepness of concentration gradient
  4. charge
  5. pressure
76
Q

Factors that influence mobility of solute molecules

A
  1. lipid solubility
  2. hydrogen bond with water
  3. molecular weight
  4. molecular shape
  5. partition coefficient
77
Q

mobility with high lipid sobility

78
Q

mobility with high hydrogen bond with water

79
Q

ratio of the distribution of a substance between two different liquid phases

A

partition coefficient

80
Q

rate of influx increases in proportion to the concentratin of the solute in the extracellular fluid

A

non-saturation kinetics

ZZZ - BIO108 - General Physiology (18 decks)

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