cellular transport figure 6-12 both diffusion and facilitated diffusion are forms of passive...
TRANSCRIPT
Cellular Transport
• Figure 6-12Both 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
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 6-11Dye 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
H2O (equal amounts entering
& leaving)
Hypotonic Solution
CYTOLYSIS
Hypertonic Solution
PLASMOLYSIS
Osmosis
Osmosis
• 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