BIOL 112 Lecture 7: Membranes

• School: McGill University
• Department: Biology
• Course: BIOL 112
• Professor: Frieder Schoeck

Document Summary

Different amino acids can be hydrophilic or hydrophobic, giving the protein hydrophilic and hydrophobic parts. Fluid mosaic contains integral and peripheral proteins. Mixing of substances allowing movement along concentration gradient. Due to random walk of molecules from thermal motions and collisions. Diffusion rate is determined by temperature, molecule size, steepness of concentration gradient, distance. Moving from low solute concentration to high solute concentration. Hypertonic solution: higher solute concentration outside cell, net water: out. Hypotonic solution: lower solute concentration outside cell, net water: in. Potassium channels only allow potassium through, using electric charge to distort membrane to allow ions through. Binds transported substance, conformational change, release into cell. Rate of diffusion is related to concentration until point of saturation where it levels off, because all proteins are occupied. 3 na+ out, 2 k+ in, using atp hydrolyzed to adp. Secondary active transport systems use established gradients to move substances.