BIO 110 Lecture Notes - Lecture 5: Chemical Energy, Potential Energy, Phosphorylation
Document Summary
Diffusion: diffusion is the tendency for molecules to spread out evenly, molecules move randomly, but net diffusion can be directional, at equilibrium, net flows are equal, substances diffuse down a concentration gradient. Osmosis: osmosis is the diffusion of water, water diffuses from the region of low solute concentration to high solute concentration. Isotonic solution: solute concentration is the same as the cell: hypertonic solution: solute concentration is greater than inside the cell, hypotonic solution: solute concentration is less than inside the cell, hypertonic or hypotonic environments create osmotic problems, Osmoregulation is necessary for life in such environments: paramecium caudatum, which is hypertonic to its pond water environment, has a contractile vacuole that can pump excess water out of the cell. In facilitated diffusion transport proteins speed diffusion: channel proteins provide specific corridors, aquaporins, ion channels, carrier proteins change shape to move the solute-binding site, no net energy input.
