fluid mosaic model Flashcards

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1
Q

describe the fluid mosaic model

A

molecules free to move laterally in the phospholipid bilayer
many components including phospholipids and proteins glycolipids and glycoproteins

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2
Q

arrangement of components of cell membrane

A

phospholipids - form bilayer
fatty acid tail face inwards and phosphate heads face outwards
intrisinc proteins span bilayer eg carrier and channel
extrinsic protiens on surface of membrane
glycolipids and glycoproteins found on exterior surface
cholesterol bonds to phospholipids hydrophobic fatty acid tails

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3
Q

arrangement of phospholipids in a cell membrane

A

bilayer with water present on either side
hydrophobic fatty acid tail repel from water so point away from water
hydrophilic phosphate head attracted to water so point to water

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4
Q

cholesterol role

A

restricts movement of other molecules making up membrane
decreases fluidity
increases rigidity

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5
Q

how cell membranes adapted for other functions

A

phospholipid bilayer is fluid so membrane can bend for vesicle formation
glycoproteins and glycolipids act as receptors and antigens involved in cell signalling and recognition

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6
Q

simple diffusion

A

lipid soluble or small move from area of high conc to low conc
down conc gradient
across phospholipid bilayer
passive so dont require energy from ATP

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7
Q

facilitated diffusion

A

water soluble larger
mov down conc gradient
through specific channel and carrier protiens
passive so doesnt require energy from atp

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8
Q

carrier and channel protiens role in FD

A

shape and charge of protein determines which substances move
channel facilitate diffusion of water soluble substances as they are a hydrophobic pore filled with water which may be gated so can open and close
carrier facilitate larger
Complementary substance attaches to binding site so protiens change shape to transport substances

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9
Q

osmosis

A

water diffuses from area of high WP to are of low WP
through a partially permeable membrane
passive so doesnt require energy from atp

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10
Q

active transport

A

substances move from area of low conc to high conc against conc gradient
require hydrolysis of ATP and specific carrier protiens

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11
Q

Describe the role of carrier proteins and the importance of the hydrolysis of
ATP in active transport

A

comp substance binds to specific carrier protein
ATP binds
hydrolysed to ADP AND PI releasing energy
carrier protein changes shape releasing substance on side of higher conc
pi released protien returns to original shape

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12
Q

cotransport na

A

NA AT from epithelial cells to blood
establishing a conc gradient of na
na enters epithelial cells down its conc gradient with glucose against its conc gradient
via a co transporter protein
glucose moves down conc gradient into blood via FD

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13
Q

Describe how surface area, number of channel or carrier proteins and
differences in gradients of concentration or water potential affect the rate of
movement across cell membranes

A

increase surface area increases rate of movement
Increasing number of channel / carrier proteins increases rate of facilitated diffusion active transport
Increasing concentration gradient increases rate of diffusion and osmosis
○ Until number of channel / carrier proteins becomes a limiting factor as all in use / saturated
● Increasing water potential gradient increases rate of osmosis

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14
Q

Explain the adaptations of some specialised cells in relation to the rate of transport across their internal and external membranes

A

folded membrane incr SA
more Protein channel and carriers for FD OR AT
lots of mitochondria making atp by aerobic respiration for AT

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15
Q

meaning of processed results

A

raw data. - has initial and final masses

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16
Q

Describe how you would use the student’s results in the table above to find the
water potential of the potato tissue.

A

calculate % change in mass
plot graph with concentration on x axis and % change in mass on y axis
find the conc where % CHANGE IS 0
use another resource to find wp of sucrose solution

17
Q

benefit of RBC having cholesterol

A

RBC free to move in in blood so cholesterol helps to maintain shape

18
Q

how to cells with no cholesterol still maintain shape

A

they cant change shape because they have a cell wall which is made of muerin and it is ridgid

19
Q

honey contains a high conc of sugar
why does putting honey on a cut kill bacteria

A

wp in bacterial cells higher than honey
water leaves bacterial cells by osmosis
loss of water stops metabolic reactions killing cell

20
Q

function of ATP hydrolase

A

atp to adp pi
releasing energy allows ions to be moved against conc gradient

21
Q

2 similarities between osmosis and diffusion

A

high to low down conc gradient
passive processes so dont require energy from ATP

22
Q

INCREASE in temp increase release of pigment

A

damage to cell surface membrane
so membrane protiens denature
increasing fluidity