Membranes as permeability barries

Question 1

what kind of molecules permeate the lipid bilayer

Answer 1

Hydrophobic molecules O2

small uncharged polar molecules H2O

Question 2

What kind of molecules cannot pass the lipid bilayer freely

Answer 2

Large uncharged polar molecules glucose

ions

Question 3

Would water have a high or low permeability coefficient

Answer 3

High as can freely pass through the membrane

Question 4

How do protein contribute to membrane permeability

Answer 4

Maintain ionic gradients
maintain pH
regulate cell volume
concentration of metabolic fuels and building blocks
extrusion of waste products of metabolism and toxic substances
generate ionic gradients for nerve and muscle

Question 5

Types are facilitated diffusion by ion channels

Answer 5

Ligand gated ion channels- nicotinic acetylcholine receptor

voltage gated ion channels- ATP sensitive ion channels

Question 6

Explain how voltage-gated ion channels opened by depolarisation

Answer 6

Sensor which is an alpha helix with lots of positive charge in plane of bilayer, depolarisation sensor up open channel

Question 7

How can you tell if the transport is active or passive

Answer 7

Depends on the concentration at the membrane potential, free energy of a favourable reaction is negative

Question 8

Which ion gradient is high within cell

Answer 8

Potassium

Question 9

Two types of co-transport

Answer 9

Symport

Antiport

Question 10

Which direction does the sodium potassium transporter pump ions

Answer 10

3 sodium out of cell
two potassium in to cell
users ATP

Question 11

Sodium potassium ATP ace is a P type ATPase what does mean

Answer 11

ATP phosphorylase aspartate producing a phosphor enzyme intermedia

Question 12

Describe the structure of the sodium potassium ATPase

Answer 12

P type ATP A’s
alpha subunit binds sodium potassium ATP
beta subunit glycoprotein directs pump to surface

Question 13

Role of sodium potassium ATPase

Answer 13

Generating the ion gradients that are used to allow secondary active transport and action potentials

Question 14

Describe the ability and capacity of the plasma membrane calcium ATPase

Answer 14

High affinity low capacity

Question 15

Describe the ability and capacity of the sodium calcium exchanger

Answer 15

Low affinity high capacity

Question 16

Sodium hydrogen exchanger

Answer 16

Uses sodium potassium ATPase, one sodium can flow down its concentration gradient whilst antiport proton out of cell

Question 17

Describe what happens in cystic fibrosis

Answer 17

CF TR cystic fibrosis transmembrane conductance regulator, mutated and doesn’t transport chloride ion out of cell, therefore get thick mucus

Question 18

Describe what happens with CF TR in diarrhoea

Answer 18

Protein kinase a phosphorylates increasing its chloride transport outside of cell, therefore increase water flowing out of cell causes diarrhoea