BI110 Lecture Notes - Membrane Transport Protein, Atp Hydrolysis, Active Transport
Document Summary
October 28, 2013: from hypotonic solution (lower concentration of solute molecules, to hypertonic solution (higher concentrations of solute molecules) Solutions on each side are isotonic when the concentrations is the same on both sides: no osmotic movement of water in either direction. Active transport requires a direct or indirect input of energy derived from atp hydrolysis. Energy required to moves substances against their concentration gradients. Depends on membrane transport proteins: specific, can be saturated. Primary active transport: the same protein that transports substance also hydrolyzes. Secondary active transport: transport indirectly driven by atp hydrolysis: transport proteins do no break down atp, instead, use a favorable concentration gradient of substance as their energy source. Moves positively charged ions across membranes: h+ pumps (proton pumps) Maintain low ca 2+ concentration: na/k+ pump. 3 na+ out, 2 k+ in for every pump cycle. Creates negative membranes potential: electrochemical gradient across membrane.