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DIFFUSION & OSMOSIS REVISITED. DIFFUSION. THE RANDOM MOVEMENT OF PARTICLES FROM AREAS OF HIGH TO AREAS OF LOW CONCENTRATION REQUIRES NO EFFORT, IT HAPPENS AUTOMATICALLY. OSMOSIS. Osmosis is the diffusion of water across a membrane No membrane= No osmosis (just diffusion)
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DIFFUSION • THE RANDOM MOVEMENT OF PARTICLES FROM AREAS OF HIGH TO AREAS OF LOW CONCENTRATION • REQUIRES NO EFFORT, IT HAPPENS AUTOMATICALLY
OSMOSIS • Osmosis is the diffusion of water across a membrane • No membrane= No osmosis (just diffusion) • If a cell membrane breaks, what will happen?
If there were no green particles, what would happen to the egg? • According to diffusion, what do the green particles want to do?
High to Low • In osmosis, water moves from areas of high to low concentration • Inside the egg there is a lower concentration of water compared to green molecules than there is outside the egg
What will happen to the egg if green molecules can’t get out?
Hypertonic • When two solutions are separated by a membrane, the one with a higher concentration of solutes is hypertonic- means OVER
Hypotonic The solution with less solutes is called hypotonic- means UNDER
Isotonic • When the two solutions have the same concentration of solutes they are called isotonic- means SAME
You pick • Find hyper, hypo, and isotonic for each example.
HOW DOES THIS RELATE TO cells? • ANIMAL CELLS
Or, the cell could get bigger until the concentrations are the same. • What is the status of the first egg, what about the second?
Can a plant cell lysis from too much osmosis? • Which structure prevents lysis?
How does a cell move molecules if it needs to go AGAINST osmosis? • Osmosis doesn’t require energy, so to go against osmosis you will have to use energy. • Most cells have methods of PUMPING molecules either in or out of the cell • This is called active transport
Active Transport • Contractile Vacuoles are a good example of active transport. • It requires ATP to pump water back out of a cell.
Passive Transport • It requires no energy for passive transport • Water will naturally move into a cell (assuming the cell is hypertonic to the water).
Active Transport Again • Some molecules are too big to get through a membrane- moving them requires ATP • Lysosomes and vacuoles work through active transport • The act of eating food is active transport
Endocytosis • Cells take material “INTO CYTOPLASM” from outside the membrane through endocytosis
Exocytosis • Cells expel materials from within the cell to the outside of the membrane by exocytosis- literally outside cytoplasm
phagocytosis • Cells “EAT” by taking large molecules into the cell. • Patrick waz here