Movement in and out of cells. (Ch 3)

• Diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
• Osmosis is the diffusion of water across a partially permeable membrane from an area of higher water potential to an area of lower water potential.
• The rate of diffusion depends on temperature, surface area, and concentration gradient
• Active transport requires energy and moves substances against their concentration gradients.
• Facilitated diffusion uses carrier proteins or channels to move molecules through cell membranes more quickly than simple diffusion.
• Active transport requires energy, while passive transport does not require energy.
• Surface area determines how many collisions can occur between the molecule and the membrane
• Temperature affects the kinetic energy of molecules which increases their speed and therefore how fast they move through the membrane
• Facilitated diffusion does not require energy but uses carrier proteins or channels to move molecules through cell membranes.
• Concentration gradient refers to the difference in concentration of solute or solvent on either side of the membrane
• Diffusion occurs when there are no barriers present
• Temperature affects the speed at which particles diffuse
• The rate of facilitated diffusion is determined by the number of carriers available on the surface of the membrane.
• The greater the concentration gradient, the faster the rate of diffusion
• The rate of osmosis depends on temperature, surface area, and pressure differences
• Active transport requires ATP, a carrier protein, and a pump