Presentation on theme: "Cellular Transport Figure 6-12 Both diffusion and facilitated diffusion are forms of passive transport, as neither process requires the cell to expend."— Presentation transcript:
Figure 6-12 Both diffusion and facilitated diffusion are forms of passive transport, as neither process requires the cell to expend energy. In facilitated diffusion, solute particles pass through a channel in a transport protein. Passive Transport – movement of substances without energy expended Passive Transport – movement of substances without energy expended
Movement across the Membrane Simple Diffusion Requires NO energy Molecules move from area of HIGH to LOW concentration
Diffusion – the movement of a substance from a high concentration to a low. Figure 6-11 Dye molecules diffuse across a membrane. At equilibrium, the concentration of dye is the same throughout the container.
Diffusion of Liquids
Facilitated Diffusion - is a process of diffusion facilitated (helped) by transport proteins
Osmosis – water transport across a membrane Hypertonic- solution with more substance than water concentration Isotonic – equal concentration of substance on both sides of the membrane Hypotonic – solution with less substance than water concentration
Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution CYTOLYSIS Hypertonic Solution PLASMOLYSIS
For a cell living in an isotonic environment (for example, many marine invertebrates) osmosis is not a problem. Similarly, the cells of most land animals are bathed in an extracellular fluid that is isotonic to the cells. Organisms without rigid walls have osmotic problems in either a hypertonic or hypotonic environment and must have adaptations for osmoregulation to maintain their internal environment.
Active Transport – requires energy to move molecules across a membrane Like an enzyme, a transport protein recognizes a specific solute, molecule or ion. During active transport, the protein uses energy, usually moving the solute in a direction from lesser concentration to greater concentration.
Transport of Large Molecules Vesicles Exocytosis Endocytosis