BIOC 3560 Study Guide - Quiz Guide: Electrochemical Gradient, Active Transport, Glucose Transporter

• School: University of Guelph
• Department: Biochemistry
• Course: BIOC 3560
• Professor: John Dawson

Document Summary

Lipid membranes are essentially impermeable to ions and polar molecules. These molecules cannot cross to any appreciable extend (e. g. na+, cl-, sugars, amino acids, water) Small uncharged molecules can cross slowly (e. g. ethanol, glycerol) Hydrophobic molecules cross quickly (e. g. steroid hormones) Gasses can also cross quickly (e. g. o2, co2 , n2, co, no) The ionic composition of the cytosol is different from the extracellular environment. There are ion concentration gradients: across the pm, across the organelle membranes. These ion gradients are actively maintained by cell, at the cost of atp. Non-polar compounds can cross membranes spontaneously and simply diffuse down their concentration gradient. In facilitated diffusion, a transmembrane protein allows a polar compound to cross the membrane down its electrochemical gradient. Ion channels act similarly, but move ions and can be gated by a liana or the membrane potential. Primary active transport moves a compound against its electrochemical gradient using atp for energy.