Fall_2010_Exam_One[1] - Cell Biology 3400 NAME_ Fall...

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Cell Biology 3400 NAME_______________________ Fall Semester 2010 Quiz I Please answer questions 1 OR 2, 3 OR 5, 4, and 6 (a total of 4 questions 25pts each). Be sure to signify clearly if you use the back page . 1a) What is the “hydrophobic effect” and how does it effect the properties of cellular membranes? (5pts) The tendency of nonpolar molecules to associate with each other in an aqueous solution to MINIMIZE THEIR ASSOCIATION WITH WATER. An increase in entropy due to the loss of structure in the water molecules drives the effect. b) Draw and name a saturated fatty acid. (5pts) Table page 47. Most people will name and draw Myristic (14:0) or Pamlitic (16:0) acid. They must draw the structure as in Figure 2-21. c) What is a lipid raft? What lipids are found in rafts? Could you distinguish a raft from non-raft components of a membrane using freeze fracture? Explain. (5pts) Lipid rafts are thickened areas of membranes most often found in the ER, Golgi and Plasma membranes. They are high in Sphingolipids and Cholesterol. Freeze fracture would NOT distinguish between rafts and normal membranes as FF is a technique that looks at surfaces and shadows and would not identify differences in membrane thickness. d) What is an integral membrane protein? (5pts) An integral membrane protein is one which is tightly associated with a cellular membrane due to the inclusion of a hydrophobic region(s) of the protein in the lipid bilayer of the membrane. Lipid anchored proteins are tightly associated but are not integral proteins as no portion of the protein penetrates or spans the bilayer e) Your colleague has given you an integral protein he has purified. Design an experiment to show that it is laterally mobile in an artificial membrane but non-mobile in the cellular membrane. (5pts) Use the protein to elicit an antibody in rabbits, purify the IgGs and then “tag” the antibody with a fluorescent molecule so that it can be visualized on or in a cell with a fluorescent microscope. Incorporate the protein into a liposome, react it with the fluorescent IgG, bleach a small area of fluorescence (i.e. IgG) on the surface of the liposome with a laser and then observe the spread of the fluorescence into the bleached area with a fluorescent scope (time lapse). It should “fill in” the bleached hole as it is mobile. Then repeat the experiment with whole cells from which the protein was originally purified. If it is immobile, the “fluorescent hole” created by the laser will be stable (not till in) as the proteins are not mobile. 2a) Name three types of transport proteins. (3pts) Transporter proteins. ATP pumps Ion Channel proteins b) Give an example of the first type, describe its function and its mode of action (i.e. mechanism [how does it work] – a drawing may help describe its mechanism). (6pts)
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This note was uploaded on 09/21/2011 for the course CBIO 3400 taught by Professor Shen,kipreos during the Fall '08 term at University of Georgia Athens.

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Fall_2010_Exam_One[1] - Cell Biology 3400 NAME_ Fall...

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