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Osmosis and Cells. Biology Chapter 8. Osmosis - the diffusion of water the movement of water from an area where there is more water to an area where there is less water controlled by the amount of solute in a solution. solutions: solute - substance dissolved by something else
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Osmosis and Cells Biology Chapter 8
Osmosis- the diffusion of water the movement of water from an area where there is more water to an area where there is less water controlled by the amount of solute in a solution
solutions: • solute- substance dissolved by something else • solvent- substance that does the dissolving
cells are usually in a watery environment remember, cells can’t stop movement of water
isotonic soln- iso- means equal a soln in which the concentration of particles OUTSIDE the cell is the same as the conc of particles INSIDE the cell water moves INTO & OUT of cell in the same amount 3 types of soln cells can be in:
hypo- means LOWER a soln in which the conc of dissolved particles OUTSIDE cell is LOWER than the same dissolved particles inside the cell water moves INTO THE CELL until conc equals out 2. hypotonic soln:
cell swells as water moves in animal cells may burst or LYSE if too much water gets in
plant cell swells; cell membrane PUSHES against cell wall TURGOR PRESSURE is maintained plant erect
hyper- means HIGHER soln in which the conc of dissolved particles OUTSIDE cell is HIGHER than the conc of same particles inside the cell water moves OUTof the cell 3. hypertonic soln
plant cells lose turgor pressure & plant wilts aka plasmolysis
Cells need certain substances- food, oxygen, ions- inside them got to go thru cell membrane transported into cell in 2 ways
1. passive transport- occurs as a cell uses NO energy to move particles osmosis & diffusion are ex of passive transport particles are small & will move from where there is more of them to where there is less 2 types of transport:
sometimes particles are too large to go thru cell membrane easily but still moving along conc gradient (from more to less) have to have help- particles will move thru the transport proteins in cell membrane this is called facilitated diffusion
2. active transport- movement of particles against conc gradient that requires cell to use energy cell is moving particles from a LOW CONC to an area of HIGHER CONC transport proteins have to be used
a. endocytosis- cell surrounds & takes in materials from env endo- within b. phagocytosis- another cell is moved into cell ex: white blood cell engulfs invading bacteria several types of active transport:
c. pinocytosis- engulfing of liquid particles d. exocytosis- expelling of waste & bits of matter exo- means outside
passive transport: no energy is used & particles are moved from MORE TO LESS active transport: energy is used to move particles from LESS TO MORE remember: