LIFESCI 7A Chapter Notes - Chapter 2.2: Contractile Vacuole, Ion Channel, Organelle
Document Summary
Explain how the chemical properties of a phospholipid bilayer allow it to act as a semipermeable membrane. Define and relate the terms tonicity, osmosis, hypertonic, hypotonic, and isotonic. Compare and contrast the different passive (simple diffusion, facilitated diffusion) and active (primary, secondary) transport mechanisms. Molecules or ions move from region of higher concentration to a region of low concentration. The difference in concentration is known as concentration gradient. Diffusion: sugar molecules become dispersed uniformly (equilibrium) Arrows under a diagram represents how molecules are allows moving to maintain equilibrium. Size differences represents which is getting favored. Small molecules can move across the lipid bilayer by simple diffusion. The more lipid-soluble the molecule, the more rapidly it diffuses. Through special channels called aquaporin (water channel) Polar and charged substances do not diffuse across lipid portion of the membrane. One way for these important raw materials to enter cells is through the proteins embedded within the membrane.
