ICPP 2 Membrane Permeability: Transport Of Ions And Small Molecules

Question 1

What is a semi permeable membrane?

Answer 1

A layer through which only allowed substances can pass

Question 2

What is passive transport independent on?

Answer 2

Permeability
Concentration gradient

Question 3

What is the net rate of transport given by?

Answer 3

Fick’s law

Question 4

What is Fick’s law?

Answer 4

J = P(C1-C2) given in exam
P- permeability coefficient
C- concentration gradient on either side

Question 5

Define passive transport

Answer 5

Solutes move by diffusion down conc. or electrical gradient
No energy required

Question 6

Define active transport

Answer 6

Solute moves against concentration gradient
Energy required

Question 7

Example of a non gated pore

Answer 7

Na+/K+ leak channels

Question 8

Example of ligand gated ion channel

Answer 8

Nicotinic ACh receptor in neuromuscular junction

Question 9

Why do patients with cystic fibrosis have thick mucus and find it hard to breathe?

Answer 9

• Mutation in cystic fibrosis transmembrane conductance regulator
• Stops Cl- form leaving (and taking 5 H2O with it)

Question 10

Explain the cystic fibrosis transmembrane conductance regulator

Answer 10

1- transports Cl- out of epithelial lung cells
2- takes 5 H2O out with it per Cl-
3- Moistens surroundings

Question 11

What impact does vibrio cholera infection have on the cystic fibrosis transmembrane conductance regulator?
What does this cause?

Answer 11

1- toxin produced
2- produces protein kinase A
3- phosphorylates cystic fibrosis transmembrane conductance regulator
4- CFTCR remains permanently open
5- Cl- and H2O leaves
6- diarrhoea

Question 12

How does cholera cause diarrhoea

Answer 12

1- toxin produced
2- produces protein kinase A
3- phosphorylates cystic fibrosis transmembrane conductance regulator
4- CFTCR remains permanently open
5- Cl- and H2O leaves
6- diarrhoea

Question 13

Types of carrier proteins

Answer 13

Uniport - one substance
Co transport- 2+ substances
- symport - same direction
- antiport - opposite direction

Question 14

Symport co-transporter

Answer 14

Transport of 2+ substances in the same direction

Question 15

Antiport co-transporters

Answer 15

Transports 2+ substances in opposite directions

Question 16

Examples of 4 co-transporters

Answer 16

• Na+/K+ ATPase
• Na+/Ca+ exchanger NCX
• Na/H+ exchanger NHE
• Na+/glucose co-transporter

Question 17

What type of active transport is in Na+/K+ ATPase?

Answer 17

Primary active transport

Question 18

What type of protein is Na+/K+ ATPase?

Answer 18

Antiport co transporter

Na in
K out

Question 19

What type of active transport is in Na+/Ca2+ ATPase?

Answer 19

Secondary active transport

Question 20

What type of active transport is in Na+/H+ ATPase?

Answer 20

Secondary active transport

Question 21

What type of protein is Na+/Ca2+ ATPase?

Answer 21

Antiport co-transporter

Na in
Ca out

Question 22

What type of protein is Na+/H+ ATPase?

Answer 22

Antiport co-transporters

Na in
H out &raquo_space; cel alkalisation

Question 23

What type of protein is Na+/glucose ATPase?

Answer 23

Symport co-transporter

Both in

Question 24

Physiological roles of transport processes

Answer 24

• Maintenance of ionic composition
• Maintenance of intracellular pH
• Regulation of cell volume
• Concentration metabolic fuel + building blocks
• Expulsion of metabolic waste + toxic substances urea
• Generation of ion gradients necessary for electrical excitability of nerve + muscle

Question 25

What type of molecules can permeate a lipid bilayer?
Examples

Answer 25

• Hydrophobic molecules - O2, CO2, N2, benzene
• Small uncharged polar molecules - H2O, urea, glycerol

Question 26

What type of molecules can’t permeate a lipid bilayer?
Examples

Answer 26

• Large uncharged polar molecules - glucose, sucrose
• Ions - H+ Cl- etc.