Passive transport through the cell membrane. Simple diffusion and facilitated diffusion. Diffusion of ions through protein channels.

Question 1

intro

Answer 1

• no ATP needed
• relies on conc gradient of transported substance for movement
• relies on KE of molecule
• selective permeability
• high concentration -> lower concentration = reaches equilibrium

Question 2

types of diffusion

Answer 2

simple
facilitated
osmosis

Question 3

carrier protein

Answer 3

binding
conformational changes
relocation
release
reform

Question 4

channel protein

Answer 4

• form hydrophilic pathways/ pores on the membrane
• allowing specific molecules to pass through

Question 5

simple diffusion - factor 1

Answer 5

concentration gradient

greater conc differences between area 1 + area 2 = faster rate of diffusion

Question 6

simple diffusion - factor 2

Answer 6

temperature

higher temp = more KE of molecules = faster rate of diffusion

Question 7

simple diffusion - factor 3

Answer 7

surface area
larger surface area = more constant particle movement per unit time = faster rate of diffusion

Question 8

simple diffusion - factor 4

Answer 8

molecular size

smaller molecules = more molecules occupy volume per unit time = faster rate of diffusion

Question 9

simple diffusion - factor 5

Answer 9

membrane permeability

more permeable = more ROR

Question 10

simple diffusion - example 1

Answer 10

gaseous exchange in the lungs

• oxygen: alveoli -> blood
• carbon dioxide: blood -> alveoli

Question 11

simple diffusion - example 2

Answer 11

nutrient absorption

glucose diffuses into small intestinal epithelium lumen to enter bloodstream

Question 12

facilitated diffusion steps

Answer 12

Question 13

facilitated diffusion - factor - 1

Answer 13

amount of transporters

more transporters (carrier/channel proteins) = faster rate of F.D

Question 14

facilitated diffusion - factor - 2

Answer 14

temperature

higher temperature = higher KE = faster rate of F.D

Question 15

facilitated diffusion - factor - 3

Answer 15

concentration gradient

greater differences between area 1 + 2 = faster rate of F.D

Question 16

facilitated diffusion - factor - 4

Answer 16

affinity

greater affinity for substrate = greater efficiency of transport

Question 17

diffusion of ions through protein channels

points

Answer 17

key features - kareen
examples - eats
types - too
mechanism - much
factors - fudge

Question 18

diffusion of ion channels - key features

Answer 18

1 - SELECTIVE PERMEABILITY
- ions are highly specific so cannot pass through any odd protein channel
- protein channels are highly specific so cannot permit entry/ exit of any odd ions

2 - PASSIVE TRANSPORT
- does not rely on ATP energy for movement
- relies on concentration gradient of transported substances

3 - GATED MECHANISM
- controls entry/ exit of specific molecules

Question 19

diffusion of ion channels - types

Answer 19

voltage gated
ligand gated
mechanical gated
leak channels

Question 20

diffusion of ions through protein channels
type 1

Answer 20

VOLTAGE GATED ION CHANNELS

• open or close in response to changes in voltage
• example: Na+/K+ channels for nerve cell membrane during action potentials

Question 21

diffusion of ions through protein channels
type 2

Answer 21

LIGAND GATED CHANNEL

• open or close depending on arrival of ligand stimulus
• example: nicotinic Ach receptors allows Na+/Ca2+ into cells = membrane depolarisation

Question 22

diffusion of ions through protein channels
type 3

Answer 22

MECHANICA; GATED ION CHANNE;S

• open or close in response to mechanical pressure
• example - sensory cells responding to sense of feeling of skin is touched

Question 23

diffusion of ions through protein channels
type 4

Answer 23

temperature gated ion channels

• open or close in response to changes in temperature
• example = TRPV1-V4

Question 24

ion channels - factors

Answer 24

1 - CONCENTRATION GRADIENT
greater concentration gradient (differences between area 1 + 2) = faster ROR

2- ION CHANNEL DENSITY
more ion channels = faster ROR

3 - MEMBRANE POTENTIAL
more differences in membrane potential = faster ROR

4 - CHANNEL CONDUCTANCE
more easily movement = faster ROR