Key Takeaways

KEY TAKEAWAYS

• Osmosis involves the transfer of water across a semipermeable membrane.

• Simple diffusion involves the transfer of a solute from an area of high concentration to an area of low concentration, not necessarily across a membrane.

• Aquaporins allow water to pass through a membrane more easily than would happen through osmosis.

• Facilitated diffusion does not require energy, while active transport usually requires ATP energy.

• The presence of an electrochemical gradient will drive the secondary active transport of certain molecules but the primary active transport happens with the sodium-potassium ATPase pump and other pumps.

• The resting membrane potential of a cell is maintained by the sodium-potassium

ATPase pump but, in certain cells, there are voltage-gated channels that allow for depolarization and repolarization.