scheffler final 2

Scheffler final 2 - 12:50:53 PM METABOLIC BIOCHEMISTRY BIBC102 Immo E Scheffler FINAL EXAM Fall 2008 All answers are to be written into the Blue

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12/12/2008 12:50:53 PM 1 METABOLIC BIOCHEMISTRY BIBC102 Fall 2008 Immo E. Scheffler FINAL EXAM All answers are to be written into the Blue Book. Leave the first inside page blank for scoring. There are 18 questions. Make sure that each answer is clearly identified with the question number at the top or left side of the page. ********************************************************************************** QUESTION 1. (15 Points) a) [5] For a phospholipid to be utilized as a carbon source it has to be degraded first by a family of enzymes. Illustrate these reactions with structural formulae for a generic phospholipid. Use ‘X’ for the group defining the phospholipid, and stop when you get to glycerol phosphate.
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12/12/2008 12:50:53 PM 2 Enzymes belonging to the group of lipases cleave the ester bonds to yield free fatty acids, or the phosphodiester bond on either side of the phosphate, depending on the specific enzyme. In this case the hydrolysis should leave the phosphate on the glycerol b) [5] Cholesterol is frequently found to be esterified with fatty acids; write a structural formula for one such molecule of cholesteryl ester . c) [5].After uptake by the digestive system and some further processing fatty acids and cholesterol are moved around the body by means of the circulatory system, but not as individual molecules dissolved in blood. Elaborate on this statement and include the terms VLDL, LDL and HDL. Briefly define these abbreviations and indicate what distinguishes them from each other. VLDL, LDL, and HDL stand for very low density lipoprotein, low density lipoprotein, and high density lipoprotein. These particles contain lipids and distinct proteins, and the ratio of lipid to protein mass determines the density. These particles are moved in the blood stream, and cells in need of lipids or
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12/12/2008 12:50:53 PM 3 cholesterol can capture them with the help of specific receptors and internalize them for further degradation. QUESTION 2. (10 Points) a) [4] What is the role of carnitine in the metabolism of fatty acids derived from food? No structural formulae required, but a schematic diagram will help. In the cytoplasm the carnitine is linked to the acyl group from acyl-CoA, and acyl carnitine is transported into the matrix of mitochondria. In the matrix carnitine is again exchanged for CoA, and free carnitine is exported for another cycle. The acyl-CoA then undergoes β -oxidation. b) [6] Fatty acids can be degraded in two different subcellular compartments. The majority are degraded in compartment A, but a specific subset are degraded in compartment B. Name the compartments. What is distinct about the subgroup degraded in compartment B? Fatty acids of “normal” size (16 or fewer carbons) are degraded in the mitochondrial matrix (A). Very long chain fatty acids are degraded in peroxisomes (B) QUESTION 3. (10 Points) a) [8] Several steps in the β -oxidation of fatty acids resemble the reactions in the Krebs cycle from succinate to oxaloacetate. Illustrate these reactions stating with the short chain fatty acid butyric acid,
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This note was uploaded on 09/11/2009 for the course BIBC 2314 taught by Professor Scheffler during the Spring '09 term at UCSD.

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Scheffler final 2 - 12:50:53 PM METABOLIC BIOCHEMISTRY BIBC102 Immo E Scheffler FINAL EXAM Fall 2008 All answers are to be written into the Blue

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