PSL300H1 Lecture Notes - Symporter
Document Summary
Atp pumps to move molecules across their concentration gradient. Membrane-spanning proteins (cid:131) globular proteins criss-cross the membrane 6-7 times (cid:131) carbohydrate chains can be attached to the proteins in the extracelluar space. Membrane permeability (cid:131) if a substance can cross the membrane by any means, the membrane is permeable to that substance: gases (ex. Co2) and lipid solubles always diffuse across the membrane: polar molecules and ions need the help of proteins (channels or carriers) to cross. September 10, 2007 specific molecules can diffuse through (cid:131) s4 is positively charged: can move when potential difference across the membrane changes, voltage-sensitive. Active transport (cid:131) mechanism to move selected molecules across cell membranes against their concentration gradient (cid:131) requires energy from atp hydrolysis (cid:131) substrate binds to protein carrier that changes conformation to move substrate across membrane. 2: saturation occurs when the concentration of molecules exceeds the number of available transporter proteins.
