BIOL 2160 Chapter : Chapter 4 Cell Membrane Transport New
Document Summary
Review cell membrane: membrane mostly phospholipids & proteins and % of each varies with structure. Crossing cell membranes: ability to cross a cell membrane depends on, size, charge and lipid solubility of a molecule, properties of the membrane, presence of membrane proteins, water moves freely across open water filled channels. Driving forces acting on molecules: direction = high energy to low, chemical forces, electrical forces. Chemical driving force: concentration gradient = eltac, from high to low concentration, down gradient, spontaneous, from low to high, up gradient, requires energy. Chemical driving force [figure 4. 1: magnitudes of chemical driving force proportional to concentration gradient. Electrical driving force: electrical driving force on charged molecules dur to a membrane potential, potential difference-separation of charge is a source of potential energy. Resting membrane potential: membrane potential given as inside relative to outside, at rest, excess anions on inside make membrane potential negative, average resting membrane potential of neurons = -70 mv.
