Unit 1: Sodium Potassium Pump Flashcards
what is the sodium-potassium pump?
vital transmembrane protein commonly found in animal cells that moves sodium ions out of the cell and potassium ions into the cell against a concentration gradient
why is sodium-potassium pump important?
generates concentration gradients between cells and their environment e.g it aids glucose absorption in the gut
How does sodium-potassium pump create a potential difference for nerve impulse transmission?
it moves three positively charged ions out of the cell and two positively charged ions into the cell
what are the two stable conformational states of the sodium-potassium pump?
has a high affinity for intracellular Na+
has a high affinity for extracellular K+
what are the stages of the sodium-potassium pump?
stage 1. in one conformational state, sodium-potassium pump has a high affinity for Na+ ions and exposes three Na+ binding sites to the cytosol.
three Na+ move in and bind to the sites
stage 2. Atpase is now able to hydrolyse an ATP molecule to ADP and phosphate. Phosphate phosphorylates the Atpase and causes a conformational change to the enzyme.
stage 3. second conformation has low affinity for Na+ ions so can only release the Na+ to extracellular fluid, pumping them out of the cell.
stage 4. second conformation has a high affinity for K+ ions so K+ form the extracellular fluid attach to the two K+ binding sites. This triggers the release of the phosphate group form the Atpase.
stage 5. the dephospho rylation restores the Atpase to its original conformation
stage 6. original conformation has a low affinity for K+ so it releases two K+ into the cell.
Now there is a high affinity for Na+ ions so the cycle repeats
what is the way to remember 2 potassium in and 3 sodium out?
Toucan - 2Kin
why does increasing the temperature increase the rate of diffusion?
molecules have more kinetic energy and so move faster
what is homeostasis?
the maintenance of a constant internal environment despite changes in the external environment
