BIOL 1020 Lecture 10: Lecture 10

• School: University of Manitoba
• Department: Biological Sciences
• Course: BIOL 1020
• Professor: Joy Stacey

Document Summary

Water diffuses from a hypotonic solution (total solute) to a hypertonic solution (total solute) Each solute diffuses down its own concentration gradient (high to low) -some water molecules can move through the membrane in spaces created by the lateral movement of lipids. Hypotonic solution: turgid (normal into central vacuole) -isotonic solution: flaccid. Hypertonic solution: plasmolyzed- cytoplasm shrivels -plants rely on the influx of water to stay turgid. Plasmolysis: cells lose water, shrivels pulls away from the cell wall. Water diffuses in, collected in contractile vacuoles, is pumped out (contractile vacuoles always pump water out) Transport proteins speed the passive movement of molecules across the plasma membrane. Channel proteins: provide corridors that allow a specific molecule or ion to cross the membrane hydrophilic channel. Translocates the solute- binding site across the membrane. Previously thought that water only crosses membranes passively (did not explain rapid movement)