LIFE 210 Lecture Notes - Passive Transport, Glucose Transporter, Electrochemical Gradient
Document Summary
Molecules can cross through channel and carrier proteins. Passive drive by diffusion, - g, with concentration or charge gradient (down hill) Active - + g, against concentration or charge gradient (up hill) G lowest for nonpolar s; highest for charged s. Large uncharged polar molecules very slow diffusion. Small uncharged polar molecules, large uncharged polar molecules, and ions all require transporters. Movement with concentration or charge gradient (down hill) electrochemical gradient. Some are gated open and close in response to signal. Movement against concentration or charge gradient (up hill) electrochemical gradient. Na+: pumped against conc. and charge gradient (+ g) K+: pumped against conc. gradient, but with charge gradient (>- g) E1-p to e2-p transition has a large g. Used to pump na+ ions against the [na+] gradient, which has a smaller + g. Na+ binds, causes conformational change high affinity for glucose. Glucose binds, conformation change flips binding site, lower affinity for sodium.
