Nerve transmission

Question 1

Stages of the sodium - potassium pump

Answer 1

1. In the first conformational state, the transporter protein has a high affinity to sodium.
2. Once sodium is attached, the protein is able to hydrolyse ATP to ADP and pi. The pi attaches to the protein, causing a conformational change.
3. The new conformation has its ion binding sites exposed to the outside of the cytoplasm. As the affinity for sodium is lower now, they detach from the protein.
4. The new conformation has a high affinity for potassium, making 2 potassium ions attach to the protein. This triggers dephosphorylation of the protein.
5. The dephosphorylation causes the protein to revert to its original conformation with the binding sites exposed to the cytoplasm.
6. This conformation has a low affinity for potassium ions so they are released into the cell. The cycle repeats…

Question 2

why is the sodium potassium pump so important?

Answer 2

It accounts for 25% of the human metabolism

Question 3

Why is the movement of sodium and potassium ions so important?

Answer 3

1. Maintaining the osmotic balance of animal cells
2. Generation of sodium ion gradient for glucose symport in small intestine.
3. Generation of sodium ion gradient in kidney tubules
4. Generation and maintenance of ion gradients for resting potential in neurons