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SCI 106 Syllabus for Exam 1

SCI 106 Syllabus for Exam 1 - Test February 13th 2008...

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Test: February 13 th , 2008 SCIENCE 106: Exam 1 Rate of diffusion (Page 27) (GarageBand: February 3 rd , 38 minutes) Firstly, diffusion must be defined. It moves molecules DOWN a concentration gradient to an area that is less concentrated. (High to Low). The rate goes faster to slower. The rate is faster if the particle is larger. If you increase the temperature, it will go faster. o So heat, size, and the concentration gradient depends the rate. o It is an inverse relationship with the size relative to rate. Osmosis (Page 27) (GarageBand: 40 minutes) Type of diffusion that only concerns water. How water, not other substances, diffuses through the membrane. Water goes to the more concentrated side in solute. So if it has more glucose on the left, it will move to the left. When diffusion stops, the osmotic pressure prevents any movement; at this point we reach equilibrium. This means that if one particle moves to the left, the left will move one to the right at the same right. The size of the osmotic pressure if directly related to the number of solute particles. o 4 glucose = pressure of 4 O.P. units. Symbol of O.P. is same as (pie, which is 3.14) RBC and physiological solutions (isotonic, hypertonic, hypotonic) (Page 27) ISOtonic is the same; therefore, the cell will stay the same size. o It will move nowhere. HYPERtonic means more. Crenation means the cell shrinks. o In a solution, if its Hypertonic, the cell will shrink as the substance leaves the cell. HYPOtonic means less. Hemolysis means the cell swells. o In a solution, if its Hypotonic, the cell will swell as the substance enters the cell. Osmosis And Water Balance (Website) o Water flows smoothly across cell membranes without needing any carrier = osmosis. Other polar or charged molecules (unless lipid soluble). o Three situations can result from water movement. Isotonic environment. Water concentration outside = water conc. inside cell. 55 multiple-choice questions
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Since most cells contain about 0.9% dissolved salts + solutes, isotonic environments must contain 0.9% salt. In this situation, water flow out = water flow in. For human cells, this is desirable state. Hypotonic environment. Water concentration outside cell is higher (e.g. pure water) than inside cell. Or, solute concentration outside cell is lower than inside cell. Result: water moves in at greater rate that moves out. 2 possible results: o If cell lacks a wall, will swell up. Can cause lysis (swelling leading to breakage) if no way to remove excess water (e.g. in blood cells). Freshwater protists (e.g. paramecium) have contractile vacuoles to pump water back out, prevent lysis.
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SCI 106 Syllabus for Exam 1 - Test February 13th 2008...

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