Biology 1202B Lecture 3: Biology 1202 Lecture 3
Document Summary
Passive transport is limited to movement down a concentration gradient. Many cellular processes require molecules to be present at a high concentration. Active transport can move molecules against a concentration gradient (i. e. , low to high concentration) 25% of a cell"s atp resources used in actively transporting molecules. Ca2+ (active transport of ions may contribute to voltage membrane potential) Movement of ions, glucose, amino acids against the gradient. Movement of ions across the membrane creates an electrical potential difference. A protein"s function is dictated by its shape. Occurs because of the difference in charges throughout the entire cell and its environment. Electrochemical gradient form primary used to drive secondary. Two different solutes carried across membrane at the same time in the same direction (cotransport) Two different solutes carried across membrane in opposite direction (exchange diffusion) Sometimes molecules are too big to move through a transmembrane protein. Membrane bound vesicle contains molecules to be removed/secreted from cell.