CELLULAR TRANSPORT (Movement of materials across a cellular membrane) Chapter 8, Section 1

Diffusion = movement of molecules from an area of high concentration to an area of low concentration Ex. Food in the kitchen, perfume/cologne in a classroom. Molecules are constantly moving around, sometimes fast sometimes slow http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

Osmosis Osmosis = diffusion of WATER across a membrane, your cells are mostly water!!! http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

Direction of Osmosis (p.196) Solute = substance that gets dissolved Solvent = substance does the dissolving Hypotonic = concentration of solutes outside of cell is lower than concentration of solutes in cytosol, water moves into cell Hypertonic = conc. of solutes outside of cell is higher than conc. of solutes in cytosol, water moves out of cell Isotonic = conc. of solutes inside & outside cell are equal, water moves in & out at equal rates

Large black dots are solute – compare amount inside vs Large black dots are solute – compare amount inside vs. outside Google – Glencoe Osmosis Virtual Lab

Practice with Osmosis: Where is there more water? Which way is the water going to move? What type of solution is this?

Hold your Wee for a Wii In 2007 a woman died participating in a California radio station contest to win a video game console. The coroner’s report indicated she died of water intoxication, hyponatremia. During the contest, participants were given two minutes to drink a bottle of water and then given another bottle to drink after a 10 minute break. This was repeated several times. Explain what you think was happening to the woman’s body and her cells.

Overconsumption of Water Hyponatremia Human body has approximately 1.25 gallons of blood. Too much water too little sodium causes imbalance. Damage to heart occurs – Why? Damage to kidneys occurs – Why? Systems shut down and coma/death can result. Cure – attempt to rebalance sodium and water. Marathon runners have died due to this condition.

Passive Transport (p.198) Cell does NOT use energy to move particles across the plasma membrane Facilitated Diffusion = passive transport of materials using proteins

Active Transport (p. 199) Cell requires energy (from mitochondria) to move particles from low concentration to high concentration

Transport of Large Particles (p. 200) Endocytosis = cell surround and takes in materials from its environment Exocytosis = cells release materials from the inside out into the environment

Practice How would you expect the amount of mitochondria (energy producing structures) in a cell to be related to the amount of active transport it carries out? Explain your answer.