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Flashcards in membranes Deck (36)
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1

what are membranes made of

phospholids in bilayers

2

what is the head of a phodpholipid

polar (hydrophillic)

3

what is the tail of a phospholipid

non polar (hydrophobic)

4

what is the hydrophobic tail made of

fatty acids and lipids

5

what is the model of the cell membrane called

fluid mosaic model

6

how is the membrane fluid

some parts are not attached to any other part of the cell and so can move freely

7

why is the membrane described as mosaic

because of the different sizes of phospholipids proteins and cholestrol

8

what is the purpose of cholesterol in the membrane

makes membrane more rigid and stable

9

what is the purpose of the glycoproteins/lipids

act as hormone receptors or cell to cell proteins

10

what is an extrinsic protein

only in the half of the membrane which is hydrophillic

11

what is an intrinsic protein

through all of the membrane

12

how do small and non polar molecules get through the membrane

they diffuse through the lipid bilayer

13

how do other molecules get through the membrane

some are too big or polar and so can't go through the lipid bilayers, instead they go through hydrophillic channel or carrier proteins.

14

what is the difference between a channel protein and a carrier protein

channel - have a hydrophilic pore which can be open and closed carrier - have a binding shape for the molecule. they change their shape to allow the molecule to cross the membrane

15

what is diffusion

movement of molecules from an area of higher concentration to an area of lower concentration

16

what is osmosis

movement of water molecules from an area go high concentration of water to an area of low concentration of water through a partially permeable membrane

17

what is a solvent

a substance that a chemical can dissolve in

18

what is a solute

the molecule that dissolves

19

what is water potential

a measure of free energy of water molecules and the tendency of water to movw

20

what is water potential measured in

kPa (kilopascals)

21

water moves from a less negative.........

water potential to a more negative water potential

22

what is the water potential in a dilute solution

more water potential energy

23

what is the water potential in a concentrated solution

less water potential energy

24

what is solute potential

how easily water molecules move out of a solution the more solute present the tighter the water molecules are held

25

what is pressure potential

pressure builds up within a plant cell due to the cell wall making the plant turgid. this pressure is pressure potential, resisting more water entry

26

what is the sign (+ or -) of pressure potential

+

27

water potential =

pressure potential + solute potential

28

what does it mean in a cell is hypertonic (plant and animal)

(plant)it is plasmolyse, the cell membrane is pulling away from the cell wall (animal) it will crenate it means that to much water is leaving the cell when in a concentrated solution in order to balance the amount of water outside the cell to the amount of water inside the cell

29

what does is mean if a cell is isotonic

it remains the same as water leaves in equal parts

30

what does it mean if a cell is hypotonic (plant and animal)

there is more water outside the cell than there is inside so more water will try and enter but the pressure potential will increase (plant) the cell wall will push out making the cell turgid(animal) the cell will explode as it has no cell wall to protect it and cant cope with the pressure