BSC 300 Lecture Notes - Lecture 7: Electric Charge, Bowel Obstruction, Weight Loss
Document Summary
Bsc 300 lecture 7- structure & function of the plasma membrane. Diffusion of a non-electrolyte requires both concentration gradient and membrane permeability. Membranes are not readily permeable to polar molecules, larger non-polar molecules. Water, though polar, is small enough to readily diffuse across membranes. Diffusion- spontaneous movement of material from a region of high concentration to low concentration. Diffusion of electrolytes depends on the electrochemical gradient. Selective permeability allows for separation and exchange of materials across the plasma membrane. Net flux- difference between influx and efflux of materials. Flux occurs by passive diffusion and active transport. Diffusion of water through a semipermeable membrane is called osmosis. Water diffuses from areas of lower solute concentration to areas of higher solute concentration. Cells swell in hypotonic solution, shrink in hypertonic solutions, and remain unchanged in isotonic solutions. Plant cells develop turgor in hypotonic solutions because cell walls prevent swelling. In hypertonic solutions the plant cell undergoes plasmolysis.