Active Transport cell uses energy ATP actively moves

Active Transport § cell uses energy (ATP) § actively moves molecules to where they are needed § Movement from an area of low concentration to an area of high concentration

Active Transport Protein Pumps -transport proteins that require energy to do work • Example: Sodium / Potassium Pumps are important in nerve responses. Protein changes shape to move molecules: this requires energy!

Active Transport Endocytosis: taking bulky material into a cell • “cell eating” • Uses energy • Cell membrane in-folds around food particle • forms food vacuole & digests food • This is how white blood cells eat bacteria!

Types of Active Transport Exocytosis: Forces material out of cell in bulk • membrane surrounding the material fuses with cell membrane • Cell changes shape – requires energy • EX: Hormones or wastes released from cell

Effects of Water on Life v. Osmosis- diffusion of water through a selectively permeable membrane v. Water is so small and there is so much of it the cell can’t control its movement through the cell membrane.

Effects of Water on Cells • Dissolved molecules (i. e. glucose, starch) are called solutes. These can evenly mix throughout water, the solvent. Water = solvent Glucose, Starch = solutes

Effect of Water on Cells Hypertonic Environment • High [solute], low [water] outside the cell. • Water will diffuse out of the cell causing the cell to shrink. Isotonic Environment • [water] = [solute] • Water moves in and out of the cell at a constant rate helping maintain equilibrium. Hypotonic Environment • High [water], low [solute] outside the cell. • Water will diffuse into the cell, causing the cell to swell.

Osmosis in Living Cells Cellulose in cell wall