Cell Processes S. Dickinson HHSBiology

How do “smells” get out of the balloon? Diffusion Diffusion Selectively permeable membrane Selectively permeable membrane Homeostasis Homeostasis Active transport Active transport Hypertonic/hypotonic/isotonic Hypertonic/hypotonic/isotonic Osmosis Osmosis

Concentration The mass of a solute in a given volume of solution The mass of a solute in a given volume of solution If you dissolve 12 grams of salt in 3 liters of water, what is the concentration of salt in the solution? If you dissolve 12 grams of salt in 3 liters of water, what is the concentration of salt in the solution?

12g/3L = 4g/L 12g/3L = 4g/L

Suppose you add 12 more grams of salt in to the solution. What would be the resulting concentration? Suppose you add 12 more grams of salt in to the solution. What would be the resulting concentration?

12g + 12g = 24 g 12g + 12g = 24 g 24g/3L = 8g/L 24g/3L = 8g/L

What if you then added another 3 liters of water to that solution. What would be the resulting concentration? What if you then added another 3 liters of water to that solution. What would be the resulting concentration?

3L + 3L = 6L 3L + 3L = 6L 24g/6L = 4g/L 24g/6L = 4g/L

4g/L; 8g/L; 4g/L Which solution would be called the most concentrated? Which solution would be called the most concentrated?

8g/L 8g/L Why? Why? –8g in 1L is more than 4g in 1L

Selectively Permeable A membrane through which some substances can pass through, but some cannot A membrane through which some substances can pass through, but some cannot

Diffusion Movement of particles from an area of high concentration to an area of low concentration Movement of particles from an area of high concentration to an area of low concentration Particles try to reach equilibrium/homeostasis Particles try to reach equilibrium/homeostasis Equilibrium/homeostasis is reached when the concentration of the solute is the same throughout the system Equilibrium/homeostasis is reached when the concentration of the solute is the same throughout the system

Diffusion Substances diffuse across membranes without requiring the cell to use energy Substances diffuse across membranes without requiring the cell to use energy Particles of a solution continue to move across the membrane even when equilibrium is reached, there is just no further change in concentration Particles of a solution continue to move across the membrane even when equilibrium is reached, there is just no further change in concentration

Active Transport (Fig. 7-19) Movement of materials against the concentration gradient Movement of materials against the concentration gradient Requires energy Requires energy Generally carried out by transport proteins in cell membrane Generally carried out by transport proteins in cell membrane Can be used to transport calcium, potassium, and sodium ions across the membrane Can be used to transport calcium, potassium, and sodium ions across the membrane

Endocytosis Membrane infolds to take in materials Membrane infolds to take in materials Pocket breaks loose to form vacuole in the cytoplasm Pocket breaks loose to form vacuole in the cytoplasm –Phagocytosis: taking in food; amoeba's use this to take in food –Pinocytosis: membranes form pockets that fill with water and break off as vacuoles in the cytoplasm

Exocytosis Membrane of vacuole fuses with cell membrane Membrane of vacuole fuses with cell membrane Forces contents out of cell Forces contents out of cell

Passive Transport Does not require energy Does not require energy

Facilitated Diffusion Does not require energy but does require a protein channel Does not require energy but does require a protein channel Movement from high [] to low [] Movement from high [] to low []

Osmosis Diffusion of water through a selectively permeable membrane Diffusion of water through a selectively permeable membrane Water moves from an area of high water concentration to an area of low water concentration Water moves from an area of high water concentration to an area of low water concentration

Hypertonic Solution has higher solute concentration than the cell Solution has higher solute concentration than the cell Water will move from inside the cell to outside the cell Water will move from inside the cell to outside the cell Figure 7-16 (pg. 186) Figure 7-16 (pg. 186)

Hypotonic Solution has a lower solute concentration than the cell Solution has a lower solute concentration than the cell Water moves into the cell Water moves into the cell

Isotonic Concentration of solutes is the same in and out of the cell Concentration of solutes is the same in and out of the cell

Utilize Fig A homeowner contracts a lawn company to add fertilizer to the lawn in order to make the grass grow better. This process is normally done by spraying a mixture of fertilizer and water onto the lawn A homeowner contracts a lawn company to add fertilizer to the lawn in order to make the grass grow better. This process is normally done by spraying a mixture of fertilizer and water onto the lawn What would happen if too much fertilizer and too little water were sprayed onto the lawn? What would happen if too much fertilizer and too little water were sprayed onto the lawn?

Can you suggest what happened to the cells of the grass? Can you suggest what happened to the cells of the grass?

In that case, was the fertilizer-water mixture hypotonic or hypertonic compared to the grass cells? In that case, was the fertilizer-water mixture hypotonic or hypertonic compared to the grass cells?

Figure 7-15 In the beaker on the left, which solution is hypertonic and which is hypotonic? In the beaker on the left, which solution is hypertonic and which is hypotonic? –The solution on the left side of the membrane is hypertonic and the solution on the right is hypotonic In this model, to which material is the membrane permeable, water or sugar? In this model, to which material is the membrane permeable, water or sugar? –Water!! This makes the membrane selectively permeable