ANA300Y1 Lecture Notes - Lecture 2: Membrane Transport, Membrane Potential, Passive Transport
Document Summary
Membrane is selectively permeable allow transport of some substances, but not others. Permeable=to pass through, if a substance can pass through any means, selective=restrictive. Cells must be able to exchange material with its immediate environment (icf/ecf) molecules need to move across the membrane transport is important: obtaining o2 and nutrients, getting rid of waste products. Allows membrane to transfer some substances but not others. Membranes are selective non-polar molecules and small molecules: easily transported across membrane, examples: o2, co2, fatty acids, water large molecules, polar molecules, and proteins: normally not transported, examples: glucose, proteins,na+ Passive: spontaneous (move along concentration gradient), downhill movement active: not spontaneous, uphill movement (against concentration gradient) Chemical driving force dependent on the concentration gradient particles move along the concentration gradient difference in concentration gradient pushes particles from higher to lower concentration force acts from higher to lower concentration chemical driving force. =concentration gradient no concentration gradient=no chemical driving force.