PSL300H1 Lecture Notes - Lecture 1: Potassium Channel, Kinetic Energy, Electric Potential
Document Summary
Membrane permeability if a substance can cross the membrane by any means, then the membrane is permeable to that substances. Eg. gases can diffuse across the membrane but polar molecules/ions/larger molecules may need the help of proteins (channels or carriers) to cross. Small, lipid-soluble molecules and gases moves down the concentration gradient. The relative rate is roughly proportional to the [ ] gradient across the membrane. With the assistance of carrier proteins movement of polar molecules down their [ ] gradient. Energy comes from the [ ] gradient of the solute (ie. passive process) Substrate binds to a protein carrier that changes conformation to move substrate (against its concentration gradient) across the membrane. When a substance is carried up its [ ] gradient without directly using atp. Kinetic energy of the movement of one substance going down its [ ] gradient powers the simultaneous transport of another substance up its [ ] gradient.
