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biology > Membranes 🧋 > Flashcards

Membranes 🧋 Flashcards

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AP® Biology flashcards
1
Q

What is the roles of membranes

A

Compartmentalise
Signalling (detect change in environment)
Controlling transporting

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2
Q

How does phospholipid structure aid cell membrane

A

Acts as a barrier, stops water soluble molecules from leaking out and getting in unwanted

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3
Q

how to phospholipids contribute to membrane formation

A

aqueous environment means heads point outward creating bi layre

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4
Q

what type of reaction holds bilayer toghether

A

weak hydrophobic reactions between tails

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5
Q

how is fluidity beneficial to membrane function

A

allows for spontaneous breaking and reforming of membranes

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6
Q

how thick is the bilayre

A

approximately 7.5 nm

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7
Q

how do unsaturated fatty acid tails effect membranes

A

make it less stable and more fluid as less packed togheter

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8
Q

when would unsaturated fatty acid tails be useful

A

in extreme environments

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9
Q

why do phospolidips get chemically modified

A

to act as signalling molecules

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10
Q

how art phospilids chemically modified

A

moving within bilayer to activate other molecules
or being hydrolysed which releases smaller water soluble molecules that bind to specific receptors in cytoplasm

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11
Q

role of glycolipids

A

maintain stability of cell membrane and to facilitate cellular recognition

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12
Q

what do glycolipids act as

A

cell markers or antigens that can be recognised by immune cells

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13
Q

impact of shorter fatty acids

A

increase fluidity, less viscous

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14
Q

why are phospholipids fluid

A

due to them being in constant movement relative to one another

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15
Q

what is the fluid mosaic model

A

phospholipids free to move, creat viscous layre, proteins randomly arranged in bilayer, free to move within layre relative to each other

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16
Q

intergal (transmembrane proteins)

A

permantely attached and span across bilayer

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17
Q

peripheral proteins

A

temporarily attached and associate with surface of membrane

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18
Q

what structure do transmembrane proteins adopt

A

single helical or beta barrels forming channels

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19
Q

glycoproteins

A

intrinsic proteins with a carbohydrate attached, have a role in adhesion and signal transduction

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20
Q

how do glycoproteins act as a receptor

A

binding site for chemical signal

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21
Q

cholesterol

A

maintains integrity and mechanical stability

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22
Q

how does cholesterol affect fluidity

A

binds to fatty acid tail increasing packing of the membrane therefore reducing fluidity of membrane

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23
Q

what does cholesterol make membranes less permeable to

A

very small water soluble molecules that would otherwise pass freely

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24
Q

active transport

A

low to high conc active process requiring atp

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25
Q

active transport step 1

A

molecule binds to receptor in channel of carrier protein outside cell, inside cell atp binds to carrier protein and is hydrolysed

26
Q

active transport step 2

A

binding of phosphate molecule to carrier protein causes protein to change shape, molecule is then realesed inside of cell

27
Q

active transport step 3

A

phosphate molecule is realesed from carrier protein and recombines with adp to form atp, so carrier protein returns to original shape

28
Q

is active transport selective

A

yes, specific substances are transported by specific carrier proteins

29
Q

bulk transport

A

active movement of large molecules

30
Q

endocytosis

A

is bulk transport of materials into cells

31
Q

phagocytosis

A

endocytosis for solids

32
Q

pinocytosis

A

endocytosis for liquids

33
Q

endocytosis process

A

cell surface membrane invaginates when it comes into contact with material, membrane unfolds intill fuses forming a vesicle, which pinches off and moves into cytoplasm for further processing inside cell

34
Q

exocytosis

A

vesicles move towards and fuse with cell surface membrane, contents of vesicle then realised outside of cell

35
Q

energy in diffusion

A

particles have KE so movement is random and unequal, particles collides slowing process down, not requiring energy as would be supplied to slowly

36
Q

facilitated diffusion

A

movement down a gradient across a membrane through protein channels

37
Q

can polar molecules travel through

A

no except for water as its so small

38
Q

can non polar molecules travel through

A

yes, but large polar ions cannot pass through

39
Q

can ions pass through

A

no

40
Q

carrier proteins

A

integral glycoproteins which bind to a solute and undergo change of shape, only bind to specific molecule, can go against conc gradient using atp

41
Q

which form of protein transport is slower

A

carrier protein 1000 molecules per second

42
Q

channel proteins

A

intergral lipoproteins, with fixed shape. only go along conc gradient

43
Q

what do channel proteins transport

A

ions and they are ion selective

44
Q

effect of alcohol

A

dissolve membrane, disrupting cells. membrane becomes more permeable and fluid and interactions cannot happen as normal

45
Q

effect of hot tempetures

A

more KE and move more, so membrane becomes more fluid and loses structure. proteins denature at high temps and if temp increases cell will completely break down

46
Q

effect of cold temps

A

water expands and ice crystals can pierce membranes, proteins can deform, permeability of membrane increases

47
Q

what helps to regulate membranes in hot temps

A

cholesterol which regulates membrane fluidity at high temps stabilising membrane and raising melting point

48
Q

solute

A

substance dissolves in solent to form a solution

49
Q

concentration

A

mass os solute in given volume of aqueous solution

50
Q

hypotonic

A

lower solute than …

51
Q

hypertonic

A

higher solute than

52
Q

isotonic

A

same levels of solute

53
Q

what is water potential

A

pressure created by water molecules as they collide with membrane or container units : kPa

54
Q

water potential of pure water

A

o kPa which is highest value

55
Q

what do solutes do to w.p

A

reduce it

56
Q

water potential in plant cells

A

w.p = solute potential + pressure potential

57
Q

water potential in animal cells

A

water potential = solute potential

58
Q

cytolysis

A

cell full of water then burst as cell surface membrane unable to stretch

59
Q

crenation

A

cell shrinks as water moves out of cell

60
Q

turgor pressure

A

pressur exerted on cell wall when cell full of water

61
Q

plasmolyse

A

plant cell protoplast shrinks and pulls away fro cell wall

biology (14 decks)

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