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 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 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 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 Osmosis- diffusion of water through a selectively permeable membrane 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