BIO130H1 Lecture Notes - Lecture 2: Uniporter, Chemical Polarity, Conformational Change
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BIO130H1 Full Course Notes
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Document Summary
Impermeable to large uncharged polar molecules or ions. Proteins are selective to either a class or maybe an individual molecule. Different cell membranes have different transport proteins. Channel mediated facilitated diffusion: the ion or large uncharged polar molecule enters/exits the cell via a (gated) channel, when the gate is opened, a lot of the molecule can cross at the same time. Transporter mediated facilitated diffusion: a proteins undergoes conformational shifts to allow a few molecules to move in or out. Create a hydrophilic pore across the membrane. Much faster transportation than a transporter; like a highway : may be gated or non-gated, non-gated = always open, gated = opening & closing is regulated via electrical, mechanical, or chemical signals. Electrical: when receiving an electrical charge, the gate opens. Mechanical: a force (eg. stretching) occurs on the membrane, the gate opens. Chemical: a ligand binds on the outside/inside of membrane, and channel opens.
