1. Molecular Interactions in Cell events
Catalysis
The Sodium-Potassium Pump
Cell Signalling

2. Sodium – Potassium pump
Study the two diagrams
What do they tell us about sodium and potassium in cells?
What do the diagrams tell us about the Na+/K+ pump?
Where are Na+/K+ particularly important?

3. Sodium – Potassium Pump
Now study the Na / K pump diagrams
Describe what is happening at each stage
In particular
Where does the protein change shape?
What causes this shape change?
When is the pump ‘open’ to intracellular contents?
When is the pump ‘open’ to extracellular contents?

4. What the diagrams tell us about sodium and potassium in cells
Na is actively removed from the cell
K is pumped actively into the cell
The Na/K pump is a dual pump Na

5. Events at each stage
The Na ions bind to the receptor sites first.
Movement is against the concentration gradient.
(2) ATP is dephosphorylated to ADP and P. The P is
released and is used to phosphorylate the protein.

6. The phosphorylation of the protein, alters the shape
of the K ion binding sites.
The opening of the protein also changes, to release
Na ions into the extracellular fluid.
The potassium binding sites fill up with K ions.

7. (5) The attachment of the 2 K ions stimulates the release
of the phosphate.
The protein closes on the extracellular side and
opens on the cytosol side.
(6) The binding sites lose their shape and the K ions are
released.

8. Learning Activities
Read DART pg 68 – 69. Check you have used correct terminology in your description
Scholar 5.2.4
Ion pumps worksheet
Advanced Higher Questions
Pool all the resources to write a job advert for a Na / K pump
Remember you can not name the successful applicant
What characteristics will the applicant need to have
What role will they undertake in the cell
What areas might they be required to work in