Lecture 9

Question 1

Roles of transport processes in cell?

Answer 1

Generation of ionic gradients

Maintain intracellular pH

Regulate cell volume

Extrusion of waste products of metabolism

Maintenance of ionic composition

Question 2

Models of membrane transport?

Answer 2

Flip-flop and rotating carriers are thermodynamically unfavourable and unlikely but can happen.

Ping-pong transport where protein goes through conformational change without moving

Ion channels which can be ligand or voltage gated

Transport processes can be saturated

Question 3

How does membrane potential determine active or passive transport?

Answer 3

If concentration gradient either side of the membrane is equal then electrical radiant will determine what way solute will flow passively. For example if the solute consists of positively charged ions and the inside of the membrane is negative the ions will move inside the cell passively

Question 4

What is concentration ratio and membrane potential?

Answer 4

Concentration ratio is the concentration of solute either side of the membrane in a ratio. Membrane potential is the difference in electric potential either side of the cell membrane.

Question 5

What is co-transport?

Answer 5

When more than one molecule is transported using a transporter. Eg symport or antiport

Question 6

Diffusion of what ion through channels is mainly responsible for membrane potential?

Answer 6

Potassium

Question 7

When is the sodium calcium antiport used?

Answer 7

Has low affinity and high capacity- used when calcium concentrations are high and it needs to be expelled quickly. An example of secondary active transport as it uses the sodium gradient.

Question 8

Give a method of hydrogen removal from the cell?

Answer 8

Sodium hydrogen exchanger which is another example of secondary active transport

Question 9

How can glucose be moved into the cell?

Answer 9

Using the glucose sodium symport another example of secondary active transport

Question 10

What are the types of co-transporters?

Answer 10

Uniports
Symports
Antiport

Question 11

What is sodium’s role in co-transport?

Answer 11

Used in antiport for calcium and hydrogen and used as symport for glucose

Question 12

Clinical relevance of transporters?

Answer 12

Cystic fibrosis- CFTR doesn’t transport chloride ions properly. No chloride means no water brought with it. That means sticky and thick mucus.

Diarrhoea- overactivation of CFTR and so excess water

CFTR= cyclic fibrosis transmembrane conductance regulator