BIO130H1 Lecture Notes - Lecture 8: Electrochemical Gradient, Alpha Helix, Atp Hydrolysis
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BIO130H1 Full Course Notes
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Impermeable to large uncharged polar molecules and ions, but can be transported with the help of membrane proteins. Membrane transport proteins: multipass transmembrane proteins (not all alpha helices), a protein lined path across the cell membrane, transport polar and charged molecules, each is selective, transports a specific class of molecule, but the specificity can vary. Passive transport: down concentration gradient, doesn"t require energy. Channel proteins: don"t interact with molecule a lot, don"t bind strongly to the molecule, don"t change conformation much. Cotransporters: one molecule down gradient, one molecule against the gradient. Light driven pump: use light energy, against gradient. Electrochemical gradient: concentration gradient plus membrane potential (electrical gradient), like charges repel. Transporter proteins: bind a specific solute, go through conformational change transporting molecule. Uniport: passive, one molecule down electrochemical gradient, direction of transport is reversible depending on concentration: glut: transports glucose down the electrochemical gradient, works in both directions (glucose in and out)