5. Membranes As Permeability Barriers

Question 1

What are the roles of the transport process?

Answer 1

Maintenance of ionic composition
Maintenance of intracellular pH
Regulation of cell volume

Question 2

What is the PMCA?

Answer 2

Plasma membrane Ca2+ ATPase
Primary active transporter
Uses ATP, converts to ADP
Transports Ca2+ from inside to outside of cell

Question 3

What is co-transport?

Answer 3

More than one type of ion or molecule may be transported on membrane transporter per reaction cycle

Question 4

What is a uniport?

Answer 4

One ion/molecule transported

Question 5

What is a symport?

Answer 5

Ion/molecule an co-transported ion/molecule both travel in same direction through protein

Question 6

What is an antiport?

Answer 6

Transported ion/molecule and co-transported ion/molecule travel in opposite directions through protein

Question 7

Describe the Na+/K+ ATPase (sodium pump) process

Answer 7

3 Na+ transported out for every 2 K+ transported in
High conc of sodium outside cell, high conc of potassium inside cell
Uses ATP

Question 8

What is the role ofCa2+ - Mg2+ - ATPase pump?

Answer 8

Pumps Ca2+ out of cell
High affinity
Transports when not much calcium in cell
Low capacity

Question 9

What is the role of Na+ - Ca2+ exchanger?

Answer 9

Pumps 1 calcium out of cell for every 3 sodium into cell 
Low affinity
Transports when high conc of calcium
High capacity
Antiport

Question 10

What is the role of Na+ - H+ exchanger?

Answer 10

Pumps 3 sodium out for every 2 potassium in, using ATP

One sodium in for every hydrogen out