March 22, 2010 What is diffusion? Osmosis? What is passive transport? Describe the makeup of the cell membrane. What types of cells have one?

Egg Demo 24 hrs in Vinegar 24 additional hours in vinegar Dissolve shell 24 additional hours in vinegar Egg increases in size 12 hrs in corn syrup Egg decreases in size

Osmosis: Types of solutions Hypotonic Outside solution has less solute than inside (less dissolved particles, more water) Water moves INTO cell Cell expands Cell may burst (lysis) Egg and vinegar

Osmosis: Types of solutions Hypertonic Outside solution has more solute than inside (more dissolved particles, less water) Water moves OUT of cell Cell shrinks Egg and Corn Syrup

Osmosis: Types of solutions Isotonic Outside solution and inside solution are equal concentrations Water moves IN AND OUT of cell at equal rates (dynamic equilibrium) Cell is unchanged

Purple Onion Lab Read the intro and answer the prelab questions before starting You need small, thin pieces of OUTER LAYER of onion

Active Transport Transport into/out of cell that requires using energy Can be for big molecules needing to enter/exit Can be for molecules needing to move against the concentration gradient (ex. move from low concentration to high concentration, they are FORCED to move!)

Being Forced to Move Cell membrane protein pumps use energy to pump things in a direction they don’t want to go Protein Pumps

Big Molecules Endocytosis Cell membrane wraps around molecule and forms a bag (vessicle) around molecule Vessicle is broken down inside the cell and then molecules move around to where they are needed Phagocytosis = cell eating Pinocytosis = cell drinking

Big Molecules Exocytosis Vessicle with trash molecule inside cell travels toward cell membrane Vessicle becomes part of cell membrane and opens to outside of cell, releasing it’s contents Active Transport Video Amoeba Feeds