Transmembrane Ion Transportation

Question 1

Explain ion transportation

Answer 1

Living cells enclosed by membranes that consist of phospholipid bilayers which are impermeable to ionic species.
Ions can cross membranes through channels and pumps, or small chaperones

Question 2

How can ion transport by facilitated?

Answer 2

Small molecular transporters

Artificial channels

Question 3

What are the mechanisms of ion transportation?

Answer 3

1) Uniport - single type of ion transported, build up of electrostatic potential
2) Symport - transport of cation and anion in same direction
3) Antiport - transport of an ion in one direction, coupled to transport of another ion of same charge in opposite direction

Question 4

What is a u-tube?

Answer 4

Aqueous layer with ion, then organic solvent with transporter, then second aqueous layer

Question 5

What is the transporter in a u-tube?

Answer 5

DCM or CHCl3

Question 6

How is ion transport monitored in u-tube?

Answer 6

Monitor second layer for the appearance of ions using ion selective electrode

Question 7

How are vesicles used to monitor ion transport?

Answer 7

Vesicles prepared from different phospholipids, the ion of interest is trapped inside the bilayer. Transport agent dissolved in DMSO and added, this carries the ion across bilayer. Ion detected using ion selective electrode or fluorescent dyes