Cells - Active Cell Transport Notes

• Active transport moves against the concentration gradient
• Cells use ATP for active transport
• Transport molecules move solute molecules across the membrane
• Proteins pumps often move ions like @@calcium, potassium, and sodium@@ which normally can’t pass through the membrane
• Protein pumps

  ==1) Solute attaches to the protein==

  ==2) ATP phosphorylates the protein==

  ==3) The protein changes shape and the solute is released on the other side of the membrane==

  ==4) The phosphate group detaches, and the protein returns to its original shape for a new round==

• %%Active transport allows a cell to maintain concentrations of small molecules that are different from the concentration of its surroundings%%
• %%An animal cell has a higher concentration of potassium ions (K+) and a lower concentration of sodium ions (Na+) than the solution outside the cell%%
• %%Nerve signals depend on these concentration differences%%
• %%The sodium-potassium pump helps cells maintain these steep gradients by shuttling Na+ and K+ across the membrane%%
• When we cry, cells in our tear glands use exocytosis to export a salty solution containing proteins