BIOL 2021 Lecture Notes - Lecture 4: Photon, Organelle, Hydrophile
12 May 2013
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Document Summary
Energy of transport comes from passive and active transport. Passive: motion occurs because of the electrochemical gradient diffusion, uses the free energy of the gradient, using the inherent energy. Active: up a gradient, coupled to an energy source, uses: atp, light, another ion gradient, this also reduces the free energy of the system. Classification of membrane proteins: channels always passive. Forms pore, selectivity filter unlike enzymes: transporters passive or active. Have to go through a conformational change, like an enzyme. General properties of both: always multi-pass transmembrane proteins, some are very specific for certain molecules or ions. A lot like enzymes: rate of transport will saturate at high concentrations. Vmax and km exist for these systems, unlike diffusion: can be inhibited by small molecule inhibitors, like enzymes. Random flip flop, allowing to flow via gradient: reduces the free energy, not necessarily due to binding of solute, concentration gradient will change. Coupled to another energy source causes conformational change: coupled transporter.
