transport across membranes Flashcards

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1
Q

what is diffusion

A

the net movement of particles from an area of higher concentration to an area of lower concentration

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2
Q

what are the properties of diffusion

A
no membrane required
no ATP required (passive)
continues until equilibrium occurs
diffusion of different particles independent
random movement of particles
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3
Q

what factors affect the rate of diffusion

A
temperature
concentration gradient
surface area of membrane
diffusion distance
size of molecule/ion
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4
Q

how does temperature affect rate of diffusion

A

increases kinetic energy therefore rate of diffusion increases

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5
Q

how does concentration affect rate of diffusion

A

increase concentration gradient increases rate of diffusion

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6
Q

how does surface area of membrane affect rate of diffusion

A

increase surface area means higher rate of diffusion

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7
Q

how does diffusion distance affect rate of diffusion

A

smaller distance means faster rate of diffusion

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8
Q

what is the effect of sizes of molecules/ions on rate of diffusion

A

smaller size means higher rate of diffusion

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9
Q

what are the properties of simple diffusion

A

only for lipid-soluble, non-polar molecules
can pass through phospholipid bilayer
examples:hormones, oxygen and carbon dioxide

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10
Q

what is facilitated diffusion

A

diffusion via channel or carrier proteins and no ATP is required (passive)

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11
Q

what goes through specific channel proteins

A

ions

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12
Q

what goes through specific carrier proteins

A

polar or water soluble molecules eg glucose or amino acids

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13
Q

How do carrier proteins work?

A

binding of molecule causes carrier protein to change shape and change of shape therefore causes amino acid to be released on other side of membrane

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14
Q

what is osmosis

A

the net movement of water from area of higher water potential to lower water potential through a semi permeable membrane until equilibrium

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15
Q

what is water potential

A

concentration of water

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16
Q

what is the highest water potential

A

0 and this is for pure water

17
Q

what are the properties of osmosis

A

passive process
continues until equilibrium
follows movement of solute as water potential decreases
random movement of particles

18
Q

what happens when theres a lower water potential inside an animal cell but higher outside

A

water enters the cell and because the plasma membrane cant stretch the cell cytolyses

19
Q

what happens when theres a higher water potential inside animal cell and lower outside

A

water leaves cell and cell cremates

20
Q

what happens when theres a lower water potential inside plant cell but higher outside

A

water enters the cell and because the plasma membrane supported by cell wall cell becomes turgid

21
Q

what happens when theres a higher water potential inside cell

A

water leaves the cell and cell becomes plasmolysed

22
Q

what is plasmolysis

A

plasma membrane of plant comes away from cell wall

23
Q

what is flaccid

A

when all cells in a tissue are plasmolysed

24
Q

what membranes are there inside cells

A

surrounding vesicles, lysosomes, smooth and rough endoplasmic reticulumn, golgi, mitochondria and chloroplasts

25
Q

whats the role of outside cell membranes

A

acts as a barrier
semi-permeable
cell recognition
cell signalling

26
Q

what is the role of inside cell membranes

A

compartmentalisation
semi-permeable
site of metabolic pathways

27
Q

what is meant by fluid mosaic model of cell

A

randomly arranged proteins in constant motion and hydrophillic heads facing outwards and hydrophobic tails facing inwards

28
Q

what is the role of phospholipid bilayer

A

its two layers of phospholipids which ONLY allows lipid soluble molecules to pass through

29
Q

what is the role of protein channels

A

allows ions to diffuse through by facilitated diffusion

30
Q

what is the role of carrier proteins

A

allows polar molecules to diffuse via facilitated diffusion

31
Q

what is the role of glycolipids and glycoproteins

A

acts as cell recognition

32
Q

what is an intrensic protein

A

protein that spans whole of bilayer

33
Q

what is an extrensic protein

A

any protein that doesnt span whole of bilayer

34
Q

what is the role of intrensic proteins

A

may be involved in cell signalling because proteins can have a multitude of tertiary structures which means that they can be complementary to particular molecules eg hormones which can bind to them on outside of plasma membrane and then cause series of reactions to occur within cytoplasm

35
Q

what is the role of cholesterol

A

binds to lipid tails of phospholipid molecule and causes them to pack more tightly and phospholipid bilayer becomes less fluid and more rigid

36
Q

how does temperature affect permeability

A

increase in temp increases kinetic energy of phospholipids and proteins and at certain temperatures plasma membrane ruptures and proteins denature

37
Q

how does solvent concentration affect permeability

A

increase in solvent concentration means more lipid dissolved and at certain concentration cell rupture occurs