8) Active Transport Systems Flashcards
Electric potential gradients
The cytoplasm has a negative electric potential relative to the extra cellular fluid
So cell is negative
The electric potential points outwards from the cell from low to high
Electric forces drive
Cations +
Anions -
Concentration potential gradient in cells
Sodium
The conc of the cell is higher outside of the cell
The conc gradients points from the cell to the outside from low to high
Diffusion moves Na into the cell
Concentration potential gradient in cells potassium
The conc is much higher inside than outside
The conc gradients points into the cell from low to night potential
Diffusion moves k out of the cell
Conc potential gradient in cells
Chlorine
The conc outside is higher than in the cell
Gradient points from the cell outwards
Diffusion moves cl into the cell
Conc potential gradient in cells
Calcium
The conc in the scarcoplasmic reticulum is higher that cytoplasm
Conc grad points into the sarcoplasmjc reticulum
Diffusion moves ca 2+ out of the sarcoplasmjc reticulum
Active transport systems
Sodium potassium ion pump
Calcium ion pump
Proton pump
An active transport systems moves na+ out of the cell so ensure the inside of the cell maintains a negative charge
Active transport moves ions from low to high electrochemical gradients
Uses energy from ATP
Sodium potassium pump
Structure
Transported ions
Drawing ✍️
Works in the presence of magnesium and ATP
hydrolysis of ATP provides energy for active transport to move
3 sodium out of the cell
2 potassium into the cell
Sodium potassium pump function
AT of sodium and potassium ensures the charge inside the cell is negative so it can become depolarised when a stimulus occurs
Operation of the sodium potassium pump
3 sodium enter from cytoplasm
ATP molecule binds to the cystolic end of the ATPase
In the presence of Mg a phosphate from ATP binds to ATPase causing it to change shape
2 potassium ions enter
Phosphate group unbinds to the ATPase and reverts back to original shape
Potassium ion leaves the cavity
Binding of sodium
Four oxygen atoms in the corner forms the sodium binding cell
12 oxygen molecules bind 3 sodiums
Binding of potassium
6 oxygens in the corners of a hexagon
12 oxygens bind 2 potassium
Use of ATP and thermal energy
Energy form ATP is used to change the affinity in the cavity
Movement of ions produces thermal energy
Pump works in the presence of magnesium
Inhibition
Varnadium ions block the pump if present in the cytoplasm
Specific inhibitors are glycosides
Pump if present in the extracellular fluid
Calcium ion pump
Structure
Transport
Transports calclium from low to high electrochemical gradient
Works in presence of Mg
Uses energy from ATP
Occurs in the sarcoplasmjc reticulum
Function of the calcium ion pump
Is to actively transport calcium ions into the sarcoplasmjc reticulum for muscle contractions to occur
