BIOL 2160 Chapter : Chapter 4 Cell Membrane Transport (Fall 2012)
Document Summary
Review cell membrane: membrane mostly phospholipids & proteins and % of each varies with structure, protein: lipid. Inner mitochondrial membranes = 76:24: phospholipids: polar head & 2 non polar tails, micelles: droplets (formed just from the cell membrane, liposomes: aqueous center used to transport anticancer drugs. Crossing cell membranes: ability to cross a cell membrane depends on: Size, charge and lipid solubility of a molecule. Presence of membrane proteins: water moves freely across open water filled channels, ions (charged particle) do not move freely across. From low energy to high (uphill: passive transport. The downfall of diffusion is that you can"t bring anymore in once you reach 50/50: membranes - barrier between ecf (water) & icf (cytoplasm, selective permeability. Non-polar and small polar cross: o2, co2, fatty acids, water. Large polar molecules, ions can"t cross: glucose, proteins, ions. Driving forces acting on molecules difference in energy across membrane. Chemical driving force: concentration gradient = c, from high to low concentration.
