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Y1 BIO > 2A: gas exchange, cell membranes and transport > Flashcards

2A: gas exchange, cell membranes and transport Flashcards

1
Q

why do cells need membranes (5)

A
  • to control what substances enter and exit the cell
  • compartmentalisation ( barrier between the organelles within the cytoplasm)
  • contains reactions within the cell
  • allows communication with the external environment
  • allows chemical gradients to be created and used
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2
Q

what are membranes made of

A

made of phospholipids

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3
Q

why can other molecules and water soluble molecules not directly pass through membranes

A

the membranes inside layer is hydrophobic therefore they travel through pathways composed of proteins (channel proteins)
-some molecules are also too big to pass through therefore they also travel using these pathways

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4
Q

how are the fats arranged in the membrane

A

in a bilyer

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5
Q

what is included in the membrane

A

phospholipid bilayer, proteins, glycoproteins, glycolipids and cholesterol

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6
Q

what are glycoproteins

A

a carbohydrate chain attatched to a protein

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7
Q

what are glycolipids

A

a chain of polysaccharides attatched to a lipid

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8
Q

what is the function of cholesterol in membranes

A

it bonds with the phospolipids and makes the membrane more rigid

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9
Q

why can only small molecules pass through the membrane

A

it is partially permeable therefore only small molecules can move between the gaps in the phospholipids

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10
Q

is the bilayer polar or non polar ? and what does this mean

A

non polar therefore only non polar substances can pass through

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11
Q

what is a channel protein

A

a protein that allows specific molecules through the bilayer

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12
Q

what is the difference between intrinsic and extrinsic proteins

A

intrinsic : span the whole width of the membrane
extrinsic : confided to the inner or outer surface of the membrane

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13
Q

what are extrinsic proteins used for

A

can be used as receptors for incoming messages from external

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14
Q

what is the function of intrinsic proteins

A

allows polar substances to pass through the bilayer using protein channels

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15
Q

what is the function of extrinsic proteins

A

allow cells to communicate with one another

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16
Q

what are extrinsic proteins (peripheral)

A

glycoproteins found on the cell surface

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17
Q

what does cholesterol do in membranes

A

regulates the fluidity of membranes

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18
Q

what is facilitated diffusion

A

when larger molecules diffuse through the membrane using carrier/channel proteins

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19
Q

what is the structure of a phospholipid

A

a glycerol head, attached to a phosphate, wuth two fatty acid tails

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20
Q

what makes the phospholipid bilayer hydrophillic

A

glycerol heads

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21
Q

what makes the phospholipids bilayer hydrophobic

A

fatty acid tails

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22
Q

why are phospholipids in a fluid mosaic structure

A

the phospholipids and proteins are constantly moving

23
Q

what do carrier proteins do

A

move large molecules into or out of the cell - down their concentration gradient

24
Q

what do carrier proteins transport

A

molecules

25
Q

how do carrier proteins transport molecules (3)

A
  • active transport
  • passive transport ie diffusion
  • facilitated diffusion
26
Q

how to channel proteins transport molecules

A

passive

27
Q

what do channel proteins do

A

form pores in the membrane for charged particles to diffuse through

28
Q

why doesn’t diffusion always allow organisms to absorb the substances they need

A

bc the substance is too big or the substance has an opposing charge to the organism

29
Q

what is required for active transport

A

ATP (energy molecule)

30
Q

how does temperature affect rate of diffusion

A

the higher the temperature, the higher the rate of diffusion and it happens quicker (more happens and in less time)

31
Q

how does surface area affect the rate of diffusion

A

the greater the surface area, more molecules that can diffuse at a time therefore less time - high efficiency

32
Q

how does diffusion distance affect the rate of diffusion

A

the shorter the distance, the quicker the molecules diffuse

33
Q

how does molecule size affect rathe of diffusion

A

the smaller the molecule the quicker it diffuses as larger molecules collide with small molecules whilst diffusing therefore they take longer

34
Q

how does concentration gradient affect the rate of diffusion

A

the steeper the concentration gradient, the higher the rate of diffusion

35
Q

what is bulk transport

A

the moving of large quantities in/ out of cells

36
Q

what happens during a bulk transport process

A

energy is used to form vesicles and to move vesicles around the cell - this vesicle is used to transport substance in and out of the cell via endocytosis or exocytosis

37
Q

what are some examples of substances that entre/enter the cell

A

hormones- insulin being released
plant cells- vesicles carry materials to make cell wall
phagocytes- engulfing pathogens

38
Q

what is endocytosis

A

when solid substances (sometimes whole organism) are taken into a cell through infolding of the surface membrane, forming a vesicle

39
Q

what is exocytosis

A

when vesicles and vacuoles move towards the surface membrane, fuse with it, and release their content outside of the cell
(some substances will be inserted into the plasma membrane instead)

40
Q

what does hypotonic mean

A

when a solution has more water than solute (dilute solution)

41
Q

what does hypertonic mean

A

when a solution has more solute than water (concentrated solution)

42
Q

what does isotonic mean

A

an equal amount of water and solute within a solution

43
Q

what does turgid mean

A

a cell at full capacity and swollen due to high liquid content

44
Q

how does SA:V ratio affect an organism transport

A

organisms with a smaller SA:V ratio cannot rely solely on diffusion for transport of substances as it would take too long

45
Q

why can multicellular organisms nor rely on diffusion for transport of substances

A

they have cells that are too far away from exchange surfaces for diffusion to suffice

46
Q

how do you calculate SA:V?

A

SA- (side x side) x how many faces
V- h x w x l

to make it decimal- do SA/V

47
Q

what are features of a good exchange surface

A
  • one cell thick
  • high blood supply
  • large surface area
  • moist lining
  • permeable
  • well ventilated
48
Q

what is the benefit of a exchange surface being one cell thick

A

short diffusion distance therefore more diffusion happens

49
Q

what is the benefit of a exchange surface having a high blood supply?

A

maintains a steep concentration gradient which facilitates oxygen (& CO2) delivery to tissues

50
Q

what is the benefit of a exchange surface having a large surface area

A

facilitates a high rate of exchange as more diffusion can happen at once

51
Q

what is the benefit of a exchange surface having a moist lining

A

allows gases to dissolve so that they can diffuse into the blood

52
Q

what is the benefit of a exchange surface being permeable

A

respiratory gases can pass through it

53
Q

what is the benefit of a exchange surface being well ventilated

A

efficient delivery of O2/CO2 to the surface

Y1 BIO (11 decks)

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