Transport

1. Transport

2. Definitions: Diffusion: Passive movement of a solute from a region of high concentration to a region of lower concentration. Osmosis: Is the movement of free water molecules through a partially permeable membrane Active transport: Movement of substances across membranes that requires the amount of energy Facilitated diffusion: Protein carrier that makes movement faster

3. Diffusion • The molecules in a solution move at high speed but the molecules moves overall slow because there are millions molecules colliding each other. • If a membrane that is permeable to both the solute and the solvent is inserted in the liquid, its doesn’t affect the diffusion pattern. • Partially diffusion: Is permeable to water and some other very small molecules, but blocks the passage of solutes such as sugar and salt. (Semi permeable or differentially permeable membranes.) • Concentration gradient: Difference between solute concentrations • Equilibrium: The condition in which all acting influences are balanced or cancelled by equal opposing forces, resulting in a stable system

4. Osmosis • When a solute (salt, sugar, protein) cannot pass through the membrane while water can • Osmotic gradient: Net diffusion of water occurs from the dilute to the concentrated solution along its own concentration gradient • Osmotic pressure: The pressure causing the water to move along the gradient • A example of osmosis is kidneys. Absorption of water from food in the gut and the reabsorption of water during urine

5. Active Transport • Slow process moving molecules and other substances across membranes, from the region low concentration to a high concentration. • Active transport is very important because it helps digest food molecules from the gut in animals and humans. • Differences between Active transport and facilitated diffusion is active transport uses energy and can move substances or molecules against a concentration gradient while facilitated diffusion can’t use energy and can’t move substances

6. Facilitated diffusion • The channels formed by some membrane proteins allow the passive movement of particular ions and molecules • The Channels allow specific molecules or transport to pass and some are not • Doesn’t need to require energy, the substances can only move by the concentration gradient • Bring molecules across the cell membrane from areas of higher concentration to areas of lower concentration