ps7s05 - MIT Department of Biology 7.013 Introductory...

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MIT Department of Biology 7.013: Introductory Biology - Spring 2005 Instructors: Professor Hazel Sive, Professor Tyler Jacks, Dr. Claudette Gardel 7.013 Spring 2005 Problem Set 7 FRIDAY May 6th, 2005 Question 1 Bovine spongiform encephalopathy (BSE, also called mad cow disease) and other similar diseases are caused by infectious particles called prions. a) Prions are made of (circle one.) Viruses bacteria DNA RNA protein lipid carbohydrate b) True or false, if false correct the sentence: T F Several new mutations arise in the brains of cows that become affected by BSE. . T F In BSE, viral factors convert proteins in the brain from one form to another. T F BSE cannot be transmitted from one cow to another. T F Spongiform encephalopathies cannot be transmitted from one species to another. In yeast, there have been found prions that behave similarly to those that cause BSE. In the case of one yeast prion, one protein conformation causes the cells to be white and another conformation causes them to be red. This confers to colonies being red or white. Assume that the protein state analogous to the infectious form of BSE causes the yeast to be red. You grow these yeast and you notice that individual colonies are mostly of a single color, but small white sectors arise within red colonies, and small red sectors arise within white colonies. c) What causes red sectors to arise within white colonies? d) If you took yeast from a red sector and replated them what color colonies would form and why? e) What causes white sectors to arise within red colonies?
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This note was uploaded on 11/11/2011 for the course BIO 7.012 taught by Professor Lander during the Fall '10 term at MIT.

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ps7s05 - MIT Department of Biology 7.013 Introductory...

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