BIO 211 Lecture Notes - Lecture 2: Aqueous Humour, Facilitated Diffusion, Lipid Bilayer
1 Dec 2020
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Document Summary
Proteins embedded in the cell membrane that regulate the flow of water. Most are ion channels, allowing passage of small, inorganic ions which are hydrophilic. Ion channels are selective and specific and may be gated or open at all time. Can be classified according to their gating mechanism. Voltage gated, ligand gated (extra-cellular and intracellular), stress activated. Transport of solute across membrane down its concentration gradient. Solute binds to carrier, it changes shape then releases solute on other side of membrane. Kinase enzyme reduces glucose concentration inside the cell by transforming glucose. Transporter proteins always bring glucose into cell. Facilitated diffusion to drive other substances against their own concentration gradients. The energy stored in the form of sodium or hydrogen ion concentration gradient is used. Plasma membranes contain several antiporters and symporters powered by the sodium. Uniporter carries only one solute at a time. Symporter carries 2 or more solutes simultaneously in same direction (co-transport) e. g. na-
