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biology > transport across cell membrane > Flashcards

transport across cell membrane Flashcards

1
Q

what are the 4 functions of the cell surface membrane

A

separating the contents of the cell from the outside environment
allows different conditions to be established in and out of the cell
regulates transport of materials
cell signalling and recognition

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2
Q

name the different parts of a phospholipid

A

1 glycerol joined to 2 fatty acid by a ester bond
1 phosphate group
hydrophobic tail
hydrophilic head

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3
Q

how wide is a cell surface membrane

A

7nm

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4
Q

what are the functions of the phospholipids in a cell surface membrane

A

to allow lipid soluble substances to come and go
to prevent water soluble substances from coming and going
make the membrane flexible and self sealing

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5
Q

what is an intrinsic protein and what are their functions

A

proteins which run all the way through the cell surface membrane
carrier proteins are used for active transport
channel proteins are used for facilitated diffusion

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6
Q

what is the function of a glycoprotein and where are they found

A

they are extrinsic proteins on the outer side of a cell surface membrane and have a receptor site linked to cell signalling

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7
Q

what are glycolipids function and where are they found

A

found on the outside and are used for cell recognition and informing other cells

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8
Q

what is the function of cholesterol in the cell surface membrane

A

regulates membrane fluidity
(stops them from melting or freezing)

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9
Q

why is a cell surface membrane a fluid mosaic pattern

A

it moves but is made up of tiny peices

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10
Q

what is transported by facilitated diffusion

A

water soluble molecules
charged molecules
glucose

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11
Q

what is transported by diffusion

A

lipid soluble molecules and gases

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12
Q

where does osmosis and diffusion occur in the membrane

A

through phospholipids

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13
Q

what is the definition of diffusion

A

net movemnet of molecules or ions from a region of high conc to low conc

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14
Q

how does conc gradient effect the rate of diffusion

A

larger the gradient the faster diffusion happens

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15
Q

how does the surface area affect rate of diffusion

A

larger SA = faster diffusion

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16
Q

how does length of pathway effect rate of diffusion

A

thinner membrane = quicker diffusion

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17
Q

how can you increase the permeability of the cell membrane to water

A

increase the number of solutes
add aquaporins

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18
Q

how do channel proteins help facilitated diffusion

A

they have aquaporins which are linned with hydrophillic amino acids and filled with water to increase the permeability of the cell surface membrane

19
Q

what happens to a carrier protein when the molecule is trying to go through the membrane

A

the molecule binds to the protein by hydrogen bonds. the protein then changes shape and rotates to deposit the molecule on the other side

20
Q

what is a solute

A

something dissolved in water

21
Q

what is a solvent

A

liquid dissolving a solute

22
Q

what is a solution

A

mixture of solute and solvent

23
Q

what is low water potential

A

a high conc of other particles in the water which could be making bonds

24
Q

what is a high water potential

A

closer to pure water

25
Q

where does water move to in osmosis

A

from from high water potential to low water potential
(to a more negative area)

26
Q

what does hypertonic mean

A

high solute and low water potential

27
Q

what does hypotonic mean

A

low solute and high water potential

28
Q

what happens when water moves into a plant cell

A

it swells and becomes turgid

29
Q

what happens when water leaves a plant cell

A

it shrinks and becomes plasmolysed

30
Q

what happens to a plant cell in a isotonic solution

A

no change
the cell is incipient plasmolysis

31
Q

what happens when water moves into an animal cell

A

it swells and burst

32
Q

what happens when water leaves an animal cell

A

it shrivels and crenates

33
Q

what is the definition of active transport

A

net movement of molecules or ions from a low to a high concentration

34
Q

what does active transport need in order to work

A

atp
carrier proteins

35
Q

explain the sodium potassium pump

A

3 Na ions from inside the cell bind to the carrier protein
atp hydrolysis releases energy and one phosphate ion attaches to the proetien
the protein changes shape and releases the Na on the outside of the cell
2 K ions bind to the protein
phosphate group is released causing the protein to change shape
2 k ions are released into the cell

36
Q

why is atp hydrolysis important to active transport

A

because breaking down atp into adp and a phosphate group releases energy which allows the carrier protein to change shape

37
Q

what is exocytosis

A

the fusion of a vesicle and a cell surface membrane to allow particles out of the cell

38
Q

what is endocytosis

A

the cell surface membrane folds in and surrounds particles from outside the cell the vesicle pulls them in to cell and the lysosomes break them down

39
Q

what are villi and microvilli

A

villi are finger like projections inside the small intestine with are covered in microvilli which make up the brush border
they increase surface area

40
Q

how does a large surface area help the exchange of materials across the villi

A

more carrier proteins so increased rate of facilitated diffusion

41
Q

how does a thin wall help the exchange of materials across the villi

A

short diffusion pathway

42
Q

how does a good blood supply help the exchange of materials across the villi

A

helps maintain the concentration gradient

43
Q

what does the lacteal do in a villi

A

takes large triglycerides which are too big to be absorbed by the capillary

44
Q

what happens in co transport in the small intestine

A

active transport of sodium ions out of the gut cells into the blood
this creates a conc gradient between the cell and the blood
the carrier proteins take the sodium ions down the conc gradient via diffusion with glucose
this increases glucose conc in the cell which then diffuse into the blood via facilitated diffusion
water enters the cell via osmosis and leaves into the blood via osmosis

biology (18 decks)

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