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bio B: form and function > b2.1 membranes and membrane transport > Flashcards

b2.1 membranes and membrane transport Flashcards

1
Q

basis of cell membranes

A

lipid bilayers

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2
Q

hydrophilic

A

molecule is attracted to water

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3
Q

hydrophobic

A

molecule is repelled by water

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4
Q

amphipathic + eg

A

both hydrophilic and hydrophobic
eg. phospholipids

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5
Q

labelled diagram of the plasma membrane

A

ipad notes

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6
Q

functions of membrane proteins [6]

A

Transport
Receptors
Anchorage
Cell recognition
Intracellular joining
Enzyme activity
TRACIE

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7
Q

stucture of glycoproteins

A

carbohydrates structure linked to protein in membrane

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8
Q

glycoproteins location + reason

A
  • on the extracellular side of the membrane
  • used for cell adhesion
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9
Q

structure of glycolipids

A

carbohydrates linked to lipid in membrane

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10
Q

glycolipids location + reason

A
  • on the extracellular side of the membrane
  • used for cell recognition
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11
Q

temperature property of unsaturated fatty acids [3]

A

low melting point
- membranes are fluid
- flexible at temperatures experienced by a cell

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12
Q

temperature property of saturated fatty acids

A

higher melting points
- make membranes stronger at higher temperatures

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13
Q

definition of endocytosis + eg

A

cell membrane can change shape slightly to form vesicle and budded off form cell surface and enter the cytoplasm as vesicle
eg. phagocytosis

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14
Q

definition of exocytosis + eg

A

vesicles can fuse with the cell membrane to export substance out of the cell
eg. secretion of enzymes

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15
Q

example of a neutransmitter-gated ion channel

A

nicotinic acetycholine receptors

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16
Q

example of voltage-gated channels

A
  • sodium and potassium channels
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17
Q

function of cell-adhesion molecules (CAMs)

A
  • used for different types of cell to cell junction
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18
Q

what does the membrane fluidity depend on

A

the fatty acid composition of the phospholipids

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19
Q

saturated fatty acid bonds

A
  • single bonds
  • straight chain structure
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20
Q

straight chain structure allows for…

A
  • more stability due to more intermolecular forces
  • reduces fluidity, flexibility and permeability
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21
Q

unsaturated fatty acid bond

A
  • double bonds
  • results in kinks within the structure
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22
Q

effect of the structure of the unsaturated fatty acid

A
  • kinks weakens the intermolecular forces -> more fluidity, flexibility and permeability in the cell membrane
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23
Q

homeoviscous adaptation can occur when

A

the cell membrane lipid composition to maintain adequate membrane fluidity

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24
Q

what happens to the composition of the phospholipid fatty acids when temperature decreases

A
  • become more unsaturated in order to maintain homeoviscosity
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25
Q

membrane lipids in cold conditions

A

becomes more unsaturated during acclimatisation
- needs to maintain fluidity and permeability to allow material exchange on cell surface
- cold temperature will reduce cell membrane’s permeability

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26
Q

diagram of saturated fatty acid

A

notes

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27
Q

diagram of unsaturated fatty acid

A

notes

28
Q

cholesterol molecule: which parts are hydophilic and hydrophobic

A

OH- hydrophilic
everything else- hydrophobic

29
Q

how is cholesterol imbedded in the fluid mosaic model

A

head to head

30
Q

why is membrane’s fluidity important for endocytosis and exocytosis

A
  • needed to transport bulk substance using a vesicle
    eg. neurotransmitter
  • vesicle has same structure as phospholipid: vesicle can fuse with the cell membrane without breaking the cell membrane
31
Q

what do endocytosis and exocytosis require

A

energy

32
Q

endocytosis

A

cell membrane can change shape slightly to form vesicle and budded off form cell surface and enter the cytoplasm as vesicle

33
Q

exocytosis

A

vesicles can fuse with the cell membrane to export substance out of the cell

34
Q

annotated diagram of endocytosis

A

notes

35
Q

annotated diagram of exocytosis

A

notes

36
Q

nicotinic acetylcholine receptors presented at

A

skeletal neuromuscular junctions

37
Q

acetylcholine

A

neurotransmitter
- act as a ligand in the ligand-gated ion channel

38
Q

function of sodium potassium pump

A

[helps maintain resting membrane potential]

39
Q

how does the lipid bilayer act as a barrier

A

hydrophobic hydrocarbon chains- low permeability to large molecules + hydrophilic particles
eg. ions, polar molecules

40
Q

what can go through using simple diffusion + examples

A
  1. small molecules
  2. soluble molecules
  3. ## non-charged moleculeseg. oxygen, carbon dioxide
41
Q

location of integral protein

A

embedded in one or both lipid layers of a membrane

42
Q

location of peripheral proteins

A

attached to one or other surface of the bilayer

43
Q

movement of water molecules across membranes by osmosis and role of aquaporins

A
  • random movement of particles
  • impermeability of membranes to solutes
  • differences in solute concentration
44
Q

how structure of channel proteins makes membranes selectively permeable

A

allows specific ions to diffuse through when channels are open but not when they are closed

45
Q

pumps use…

A

energy from ATP to transfer specific particles across membranes so they can move particles against a concentration gradient

46
Q

what allows selective permeability in membranes [2]

A
  1. facilitated diffusion
  2. active transport
47
Q

why is simple diffusion not selective

A

depends only on the size and hydrophilic/phobic properties of particles

48
Q

function of cholesterol [3]

A
  1. acts as a modulator of membrane fluidity
  2. stabilises membranes at higher temperatures
  3. preventing stiffening at lower temperatures
  4. maintains necessary orderly arrangement of phospholipids
  5. maintains impermeability to hydrophilic particles
    eg. sodium and hydrogen ions
49
Q

how does voltage-gated sodium channels only allow sodium to go through?

A
  • diameter
  • negatively charged
50
Q

what is essential for diffusion

A

concentration gradient

51
Q

facilitated diffusion

A

passive movement of a particle across a cell membrane via a channel protein

52
Q

processes in nerves that require a membrane protein

A
  1. active transport of sodium
  2. propagation of an action potential
  3. binding of neurotransmitter
53
Q

phospholipid structure

A
  • hydrophilic head made from phosphate and glycerol
  • 2 hydrophobic tails made from fatty acids
54
Q

what are phospholipids held together by

A

hydrophobic interactions

55
Q

how are phospholipid layers stabilised

A

by interaction of hydrophilic heads and surrounding water

56
Q

why is fluidity important in the plasma membrane

A

important in breaking and remaking membranes
eg. endocytosis, exocytosis

57
Q

what cannot use simple diffusion [3]

A
  1. large molecules
  2. charged molecules
  3. non-soluble
    eg. water, glucose
58
Q

features of the fluid mosaic model [4]

A
  • flexible, adaptable and in motion
  • have freedom of movement
  • individual phospholipids are attracted to each other by weak attraction
  • cumulative effect: very strong membrane
59
Q

how do pump proteins work

A
  • molecule binds to the active site of the pump
  • ATP transfers phosphate to the protein
  • results in conformational change in the shape of the protein pump
  • molecules is pushed to the other side of the membrane
60
Q

voltage-gated sodium channel used + found in

A

used in: facilitated diffusion
found in: neurons

61
Q

how does nicotinic acetylcholine receptor work + diagram

A
  1. acetylcholine binds to it
  2. sodium comes in: voltage to ard -50 mV
    - more sodium go in
    - new action potential created
  3. impulse continues
    - nicotine can also bind and open the receptor
62
Q

what is the healthiest type of fatty acid

A

monosaturated cis fatty acid
- bends

63
Q

how does cholesterol cause the membrane to be more fluid

A
  • forces a gap between the membrane
  • moves phospholipid away form each other to ensure that theyre not too closely packed
64
Q

non-polar means its hydrophilic/hydrophobic?

A

hydrophobic

65
Q

proximal convoluted tubule

A

how glucose goes through and comes back
- diagram
1. sodium potassium pump generates low sodium concentration
2. low Na+ concentration is generated inside the cell
3. higher Na+ concentration in the lumen, this allows Na+ to diffuse into the cell using the sodium-dependent glucose co-transporter
4. since glucose is co-transported into the cell, the cell has a higher glucose concentration
5. glucose will diffuse through the glucose channel proteins and back into the blood
6. this is known as indirect active transport

66
Q

what happens when an action potential reaches motor end plates

A

neurotransmitter is released

bio B: form and function (9 decks)

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