Membrane Structure Flashcards

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1
Q

organs definition

A

specialized structure in the body that perform specific life processes

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2
Q

organelles definition

A

specialized structures inside the cell that perform specific cellular processes

often surrounded by a membrane

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3
Q

cell fractionation

A

a method of separating cell parts to study their function

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4
Q

homogenization definition

A

the disruption of cell membrane without damaging organelle

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5
Q

centrifuge

A

instrument that spins a high speeds to spearate contents by density

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6
Q

4 ways to rupture the plasma membrane

A
  • break cells with high frequency
  • use a mild detergent
  • use high pressure by forcing cells through a small hole
  • shear cells between a close fitting rotating plunger
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7
Q

steps to cell fractionation

A
  1. homogenize
  2. centrifuge
  3. decant supernatant
  4. repeat centrifugation at higher speeds to separate into smaller components
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8
Q

pellet

A

larger, more dense components of tissue

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9
Q

supernatant

A

lighter suspended in liquid above the pellet in tissue

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10
Q

plasma membrane

A

aka cell membrane all cells and organelles are surrounded by it

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11
Q

what is the membrane composed of?

A
  • phspholipids
  • membrane proteins (integral, peripheral)
  • carbohydrates
  • cholesterol
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12
Q

what is each layer called in a phospholipid bilayer

A

leaflet

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13
Q

what environment is the phospholipid bilayer in?

A

water is on both sides -> cell is in water environment and the cell interior is also a water environment (polar)

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14
Q

how is the phospholipid arraged in the phospholipid bilayer

A
  • hydrophobic tails face inward forming a hydrophobic core
  • hydrophilic heads face outwards
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15
Q

what are the two locations classification of membrane proteins

A

integral, peripheral

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16
Q

what are the classification of integral proteins

A
  • polytopic transmembrane, sinlge-pass, multi-pass
    -monotopic
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17
Q

what are the classifications of peripheral proteins

A
  • extracellular
  • intracellular
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18
Q

what does polytopic mean?

A

faces both sides of membrane

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19
Q

transmembrane definition

A

spans entire phospholipid bilayer

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20
Q

single pass protein definition

A

crosses membrane once

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21
Q

multi-pass protein definition

A

crosses membrane several times

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22
Q

monotopic definition

A

associated with membrane on one side, does not span entire bilayer

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23
Q

how are non peripheral mombrane proteins bound?

A

non-covalently to either surface of the membrane

does NOT enter the leaflet

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24
Q

functions of membrane proteins

A
  • receptor
  • enzymatic activity
  • recognition
  • attachment
  • transport
  • cell adhesion
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25
Q

types of transmembrane proteins

A
  • receptor protein
  • channel protein
  • gated channel protein
  • transport protein
  • glycroprotein protein
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26
Q

receptor protein

A

has a binding site to fit the molecule which acts as a chemical signal/messenger,

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27
Q

result of binding in receptor protein

A

causes a conformational change in receptor protein, which results in a relaying message to the interior of the cell

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28
Q

enzymatic activity

A

protein has a binding sit for molecule, binding results in a chemical reaction that changes the substrate to a new product

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29
Q

recognition protein

A

glycoprotein, surface carbohydrate groups help identifycell (eg antigens)

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30
Q

what does an attachment protein attach to?

A

interior cytoskeleton, exterior extacellular matrix (ECM)

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31
Q

what does the attachment protein do?

A

provide structural support

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32
Q

where does the extracellular cell face?

A

exterior/outside of the cell

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33
Q

what do extracellular proteins attach to?

A

the extracellular matrix, ECM

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34
Q

what is the fuction of ECM(extracellular matrix)

A
  • supports cell structure
  • anchors cell
  • separates tissues
  • functions in cell signalling
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35
Q

components of ECM

A

a matrix of glycoproteins secreted by cells, it varies with type of tissue

36
Q

where are intracellular proteins attached?

A

inner membrane surface

37
Q

what do intracellular cytoskeleton protein attach to?

A

cytoskeleton of cell

38
Q

describe the intracellular cytoskeleton

A

a network of fibers extending throughout the cytoplasm

39
Q

what does it mean by the intracellular cytoskeleton being dynamic

A

can be quickly dismantled and reassembled in a new location

40
Q

what are the functions of the cytoskeleton

A
  • mechanical support to cell
  • cell motility
41
Q

how does cytoskeleton support cell structure?

A
  • anchorage for organelles
  • maintain cell shape
    critical for animal cells as there is no cell wall
42
Q

what does motility of a cell mean in regards to the cytoskeleton

A

movement of cell -> change in cell location
movement of parts, vesicles, chromosomes, etc

43
Q

what are the components of the cytoskeleton

A
  • micro filament - actin
  • intermediate filament
  • microtubules - tubulin
44
Q

types of transport proteins

A

channel, carrier/pump

45
Q

types of channel transport protein

A

ungated, gated

46
Q

describe the channel proteins

A
  • act like tunnels
  • molecules move through protein passively
47
Q

what types of particles to channel proteins move?

A

small molecules or charged ions

48
Q

describe an ungated channel protein

A

always opened aka leak channels

49
Q

describe a gated channel protein

A

has open and closed conformations changes stimulated by changes in external environment,

50
Q

describe the carrier/pump proteins

A
  • acts like turnstile
  • undergoes conformational change to allow molecules through
51
Q

what does it mean by cell adhesion proteins

A

structures that connect cell to cell, in animal cells

52
Q

what are the types of cell adhesion proteins

A
  • channel-forming
  • ocluding junction
  • anchoring junction
53
Q

describe the channel forming protein

A

provides channel between adjacent cells for passage of small molecules and ions

54
Q

describe the occluding junction protein

A

fuses membranes of adjacent cells, forms impermeable barrier between cells

55
Q

what is another name for anchoring proteins

A

desmosome

56
Q

describe the anchoring/desmosome proteins

A

desmosomes bind to desmosomes on adjacent cell

57
Q

what does a desmosome do?

A

helps resist shearing force when cells are under mechanical stress

58
Q

where are desmosomes attached?

A

cytoskeleton

59
Q

what is the name of occluding proteins?

A

tight junctions

60
Q

what is the name of channel forming proteins?

A

gap junctions

61
Q

example of gap junction attachements

A

muscle tissue

62
Q

example of tight junction attachment

A

intestinal lining

63
Q

example of desmosome

A

bladder tissue

64
Q

functions of integral proteins

A

receptor, enzymatic activity, recognition, attachment, transport, cell adhesion

65
Q

peripheral protein functions

A

recognition
attachment

66
Q

glycoprotein makeup

A

carbohydrate + protein

67
Q

glycolipid makeup

A

carbohydrate + lipid (phospholipid)

68
Q

where are carbohydrates relative to the cell

A

extracellular

69
Q

what are the function of cell surface carbohydrates?

A
  • identifies the cell, helping other cells recognize it
  • acts as a signal for communication
70
Q

what is membrane fluidity affected by?

A
  • saturation of fatty acid
  • hydrophobic restrictions
  • cholesterol and temperature
71
Q

what are the types of movement within the membrane?

A
  • lateral diffusion
  • rotation
  • swing
  • flexion
72
Q

what is lateral diffusion movement within a membrane?

A

movement accross the same leaflet (phospholipids transpose with neigboring molecules)

73
Q

what is rotation movement within a membrane?

A

when a individual molecule rotates quickly around its axis

74
Q

what is swing movement within a membrane?

A

from side to side

75
Q

what is flexion movement within a membrane?

A

contraction movement

76
Q

transverse diffusion aka…

A

flip flop

77
Q

transverse diffusion

A

movement from one leaflet to another

78
Q

what enzyme facilitates transverse diffusion

A

flippase

79
Q

why is transverse diffusion rare?

A

the hydrophilic head of phospholipid must go cross the hydrophobic core to get the leaflet

80
Q

properties of cholesterol

A

large molecular size and non polar

81
Q

what is the impact of cholesterol having a large molecular size

A

can interrupt intermolecular forces of attraction

82
Q
A
83
Q

what is the impact of cholesterol being non polar

A

stabilizes hydrophobic interactions

84
Q

what does cholesterol do at a low temperature?

A

the phospholipid moves around less, squeezes phospholipids and increases fluidity -> large molecular size

85
Q

what does cholesterol do a high temperature?

A

pulls together the bilayer -> non polar

86
Q
A