9) Unit 1 - Ion Transport Pump

Question 1

What does the Na/K pump do?

Answer 1

Transports ions against a concentration gradient using energy.

Energy comes from the hydrolysis of ATP so active transport

Question 2

Describe the process of the Na/K pump

Answer 2

1) involves intrinsic proteins that span the membrane
2) 3 sodium ions bind to the carrier protein on the cytosol (inside) side of the membrane
3) at the same time, the carrier protein receives a phosphate from ATP and is phosphorylated
4) this causes conformational change of the carrier protein. With its new shape the protein pumps 3 Na ions through the membrane
5) At this point, the carrier has the shape it needs to bind 2 potassium ions outside the cell
6) when the potassium ion binds, the phosphate group is released, (dephosphorylation) and the carrier protein is restored to its original shape
7) the change in conformation allows the carrier protein to pump 2 potassium ions inside the cell. The process is ready to begin again.

Question 3

Different conformations of the Na/K pump have different ____________ for sodium and potassium

Answer 3

Affinities

Question 4

List 4 functions of the Na/K pump

Answer 4

• maintaining osmotic balance in animal cells
• generation of ion gradient for glucose symport in small intestine
• generation of long term maintenance of ion gradient for resting potential in neurones
• generation of ion gradient in kidney tubules

Question 5

What types of proteins are uniport, symport, and antiport

Answer 5

Transporter proteins

Question 6

Describe uniport

And is it passive or active

Answer 6

Transports one molecule across the membrane along a concentration gradient

Passive

Question 7

Describe symports and give an example

Answer 7

Where transporting one molecule results in the transportation of another in the same direction

E.g glucose symport

Question 8

Describe antiport and give an example

Answer 8

Transportation of two molecules in opposite directions

E.g Na/K pump