Exam 3 Study Guide - The most direct evidence that a...

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The most direct evidence that a molecule is hydrophilic would be that it has charges and partial charges. Phospholipid has a polar head and nonpolar fatty acid tails. The Fluid Mosaic Model replaced the sandwich model when freeze-fracture experiments showed that globules of protein extend into the center of a plasma membrane. The fluid mosaic theory takes its name from the fact that it predicts that the membrane surface looks like an irregular, shifting patchwork of phospholipid and protein. Treelike structures on surface of membrane are probably oligosaccharides of glycoproteins. The force that allows instant repair and holds the phospholipids in their bilayer is most directly the attractions between H2O. Proteins function as pore lines, carrier molecules, and receptor molecules. The role of cholesterol is to regulate the fluidity of the phospholipid bilayer (phytosterols in plants and hopanoids in bacteria). Integrins attach the extracellular matrix to the membrane. Cell that is decreasing in T will incorporate more unsaturated fatty acids. Model will be rejected when it can no longer predict experimental outcomes successfully. Diffusion rate would be the fastest if the diffusing molecule were small and nonpolar. Cell A is metabolically quiet. Cell B is actively consuming O2. O2 will diffuse more quickly into Cell B because the concentration gradient is steeper. Electrochemical gradient. Battery. Membrane polarization is established by electrogenic pumps. Clathrin is responsible for the infolding of the membrane during receptor-mediated endocytosis. In lab we expected there would be glucose in the beaker and that the inside of the dialysis bag would be blue-black since starch is too big to pass through. The strip turned pink since ammonia is basic. Isoosmotic= equilibrium Osmolality depends on number of particles. Animal cell in dilute salt solution neither gains nor loses water and membrane is not stretched tight: cell is isosmotic to environment, equal water potential between cell and environment, and equal osmotic potential. Plant cell is dilute salt solution neither gains nor loses water but protoplast is pushed out tightly against cell wall: the cell and the environment have the same water potential. The greater osmotic effect of NaCl is caused by the fact that NaCl is smaller and dissociates into ions. Hyperosmostic > isosmotic> hypoosmotic. Red blood cells shriveled because the osmotic potential of the cell was higher than that of the surrounding solution.
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Cell A is hyperosmotic to its surrounding b/c its osmotic potential is more negative than its surroundings. If you put more salt solution on the outside of plant cell water will move out. The plant cell does not change in appearance b/c the cell decreased its pressure.
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