Molecules need to move across membranes in cells… Image modiified from: http://www.accessexcellence.org/AB/GG/importProt.html IN food carbohydrates sugars, proteins amino acids lipids salts, O 2 , H 2 O OUT waste ammonia salts CO 2 H 2 O products How does that happen?
1. Hypotonic -solute outside cell less than inside; water moves into cell; cell swells
2. Hypertonic- solute outside cell greater than inside; water moves out of cell; cell shrinks
3. Isotonic -solute outside cell equals inside; no net movement of water.
HYPOTONIC ISOTONIC HYPERTONIC solute outside ‹ inside Net movement of water into cell Animal cells: swell & burst = CYTOLYSIS Plant cells increase TURGOR PRESSURE solute outside = inside Net movement of water in and out of cell is equal No change in size solute outside > inside Net movement of water out of cell Animal cells: shrink = CRENATION Plant cells: can’t shrink due to cell wall Cell membrane pulls away from cell wall= PLASMOLYSIS
Types of FacilitatedDiffusion 2. Carrier protein -proteins that bind to specific substances, carry it across the cell membrane , and release it. Animation from: http://bio.winona.edu/berg/ANIMTNS/facdifan.gif