BSC 2010C Lecture Notes - Lecture 7: Active Transport, Passive Transport, Facilitated Diffusion
Document Summary
Controls passage of substances in and out of cell. Ectotherms" phospholipid comp is dependent on the environment. Hydrophobic region penetrates and binds to hydrophobic tails of membrane bilayer. Can extend all the way through both sides of the plasma membrane. Some extend through only one side of the plasma membrane. Don"t penetrate or bind to hydrophobic tails of the plasma membrane. Are bound to one side of the plasma membrane only. Membranes regulate passage in and out of cell. Small molecules can cross more easily than large. Transport proteins assist molecules that can"t cross easily. Binds to molecule to be transported then changes shape to facilitate passage. Molecule avoids contact with hydrophobic tails of lipid bilayer. 3 sodium ions (na+) are pumped out of cell. 2 potassium ions (k+) are pumped into cell. Movement of particle from an area of high concentration to an area of low concentration. Diffusion of water across a semi permeable membrane.
