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biology > chapter 5 - plasma membranes > Flashcards

chapter 5 - plasma membranes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is compartmentalisation

A

the formation of seperate membrane-bound areas

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2
Q

what is the fluid mosaic model

A

phospholipids are free to move giving the membrane flexibility and because the proteins embedded in the bilayer vary in shape, size and position

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3
Q

what are intrinsic proteins

A

proteins embedded through both layers of a membrane.

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4
Q

what are the 2 types of intrinsic proteins

A

channel proteins - provide hydrophilic channel that allows passive movement of polar molecules
carrier proteins - used for both passive and active transport

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5
Q

what are glycoproteins

A

intrinsic proteins with carbohydrate chain attached

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6
Q

what are uses of glycoproteins

A

used in cell adhesion
receptor for cell signalling

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7
Q

what are glycolipids

A

lipids with attached carbohydrate chain. these molecules are called antigens

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8
Q

what are extrinsic proteins

A

proteins present in one side of the bilayer

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8
Q

what is cholesterol

A

a lipid with hydrophilic end and hydrophobic end which interacts with phophate head and fatty acid tail pulling them closing to stabilise membrane
regulates fluidity of membrane by preventing membrane to group too closely

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9
Q

factors affecting membrane structure

A

temperature
solvents - non-polar like alcohol dissolve membranes

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10
Q

what is diffusion

A

diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration

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11
Q

what are the factors affecting rate of diffusion

A

temperature
concentration difference

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12
Q

what is simple diffusion

A

diffusion in absence of a barrier

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13
Q

why are membranes partially permeable

A

only small non-polar molecules can freely diffuse through

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14
Q

what are the factors affecting rate of diffusion across a membrane

A

surface area
thickness of membrane

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15
Q

what is facilitated diffusion

A

diffusion of particles across a membrane through protein channels

16
Q

why are membranes with protein channels selectively permeable

A

most protein channels are specific to one ion/molecule

17
Q

factors affecting facilitated diffusion

A

temperature
concentration difference
surface area
thickness of membrane
number of protein channels

18
Q

what is active transport

A

movement of particles from a region of lower concentration to a region of higher concentration. this requires energy and carrier proteins

18
Q

how does carrier proteins act as pumps

A

molecule to be transported binds on receptors of carrier protein. ATP on inside of cell binds to carrier protein and is hydrolysed to ADP and phophate which binds to carrier protein , opening it up. Molecule is released into cell and phophate is now released so carrier protein closes up and recombined with adp to form atp

19
Q

what is bulk transport

A

form of active transport for large molecules such as enzymes and hormones

20
Q

what is endocytosis

A

bulk transport of material into cells

21
Q

what are the 2 types of endocytosis

A

phagocytosis ( solid)
pinocytosis ( liquid)

22
Q

what is exocytosis

A

bulk transport of material out of cells

23
Q

what is osmosis

A

diffusion of water across a partially permeable membrane

24
Q

what is water potential

A

pressure exerted by water molecules as they collide with a membrane

25
Q

what is water potential of pure water

A

0

26
Q

what is cytolysis

A

bursting of animal cell due to increased hydrostatic pressure as they have no cell wall and cannot stretch much

27
Q

what is crenation

A

when animal cell loses water resulting in reduction of volume

28
Q

how is cytolysis and crenation prevented

A

animal cells have isotonic solution such as blood plasma for equal water potential

29
Q

why dont plants burst as much as animal cells

A

have cell wall so can withstand higher pressure ( turgor) which prevents entry of more water ( turgid)

30
Q

what is plasmolysis

A

lower water potential in plant cell so cell shrinks and protoplast is pulled against cell wall and shrinks

biology (17 decks)

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