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

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?

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?

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

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.

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.

(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.

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