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YEAR 1 BIO > membranes > Flashcards

membranes Flashcards

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Biology 101 flashcards
1
Q

what are membranes made of

A

phospholids in bilayers

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2
Q

what is the head of a phodpholipid

A

polar (hydrophillic)

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3
Q

what is the tail of a phospholipid

A

non polar (hydrophobic)

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4
Q

what is the hydrophobic tail made of

A

fatty acids and lipids

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5
Q

what is the model of the cell membrane called

A

fluid mosaic model

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6
Q

how is the membrane fluid

A

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

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7
Q

why is the membrane described as mosaic

A

because of the different sizes of phospholipids proteins and cholestrol

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8
Q

what is the purpose of cholesterol in the membrane

A

makes membrane more rigid and stable

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9
Q

what is the purpose of the glycoproteins/lipids

A

act as hormone receptors or cell to cell proteins

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10
Q

what is an extrinsic protein

A

only in the half of the membrane which is hydrophillic

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11
Q

what is an intrinsic protein

A

through all of the membrane

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12
Q

how do small and non polar molecules get through the membrane

A

they diffuse through the lipid bilayer

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13
Q

how do other molecules get through the membrane

A

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

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14
Q

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

A

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

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15
Q

what is diffusion

A

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

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16
Q

what is osmosis

A

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
Q

what is a solvent

A

a substance that a chemical can dissolve in

18
Q

what is a solute

A

the molecule that dissolves

19
Q

what is water potential

A

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

20
Q

what is water potential measured in

A

kPa (kilopascals)

21
Q

water moves from a less negative………

A

water potential to a more negative water potential

22
Q

what is the water potential in a dilute solution

A

more water potential energy

23
Q

what is the water potential in a concentrated solution

A

less water potential energy

24
Q

what is solute potential

A

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

25
Q

what is pressure potential

A

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
Q

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

A

+

27
Q

water potential =

A

pressure potential + solute potential

28
Q

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

A

(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
Q

what does is mean if a cell is isotonic

A

it remains the same as water leaves in equal parts

30
Q

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

A

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

31
Q

what is incipient plasmolysis

A

when the water potential outside and inside a cell is equal there is no net movement half of the cell is plasmolysed and half is not

32
Q

what is ficks law

A

rate of diffusion is in proportion to (surface area x concentration gradient) / length of diffusion pathway

33
Q

why is the rate of diffusion only ‘in proportion to’ and not equal to

A

because there are other factors that affect the rate of diffusion

34
Q

what other factors affect the rate of diffusion

A

tempertaure size of diffusing molecules chemistry of diffusing molecules (polar or non polar)

35
Q

what is active transport

A

molecules move from a low concentration to a high concentration against the concentration gradient

36
Q

what does active transport need to take place

A

ATP for energy

YEAR 1 BIO (16 decks)

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