BIO 209 Lecture 14: Membrane Transport Lecture 1
Document Summary
Solutes have different rates of diffusion depending on solute polarity and solute concentration gradient: membrane is selectively permeable. Transporters- tend to have high selectivity specificity: channel proteins- Simple diffusion: activation energy for diffusion through the membrane is high process of hydration shell removal is endergonic, moving across the membrane with the concentration gradient, moves from high concentration to low concentration. Involves specific binding to sites on the transport that leads to a conformational change. Transporter proteins reduces activation energy by forming noncovalent bonds with a dehydrated solute to replace hydrogen bonding. This creates a hydrophilic transmembrane pathway: active transport. Requires energy: molecule is typically moving against its concentration gradient. Polar solvents need to pass through the hydrophobic interior of the membrane: water forms hydration shells to interact with the solute. Energy is required to move the water away: a noncovalent reaction comes in to replace this.