Study Guide Exam 4

Study Guide Exam 4 - 1 CHEM 1530 Exam#4 Study Guide(Chap 26...

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1 CHEM 1530 Exam #4 Study Guide (Chap 26 & 29) Spring 2008 (4/8/08). Instructor: JDavis Chapter 25.5 – 25.8: Lipid Metabolism 1. Know what is Beta-oxidation is; how many NADH, FADH 2 , and Acetyl CoA molecules are made in a single spiral. This should include the nature of the four reactions and basic knowledge of what happens chemically in each reaction. β-oxidation pathway: more of a spiral than a cycle. - The name refers to the oxidation of the carbon atom, β (beta) to the thioester linkage. - β-Oxidation of the (3rd) carbon atom beyond the thioester linkage, is the key process in the pathway. - STEP 1: The first b-oxidation: The oxidizing agent FAD removes hydrogen atoms from the carbon atoms a and b to the C=O group in the fatty acyl-SCoA, forming a carbon–carbon double bond. STEP 2: Hydration: A water molecule adds across the newly created double bond to give an alcohol with the –OH group on the b-carbon. STEP 3: The second b-oxidation: NAD + is the oxidizing agent for conversion of the b-OH group to a carbonyl group. STEP 4: Cleavage to remove an acetyl group: An acetyl group (2C) is split off and attached to a new coenzyme A molecule. - What’s left behind is an acyl-SCoA that is two carbon atoms shorter. ► Fatty acids with even numbers of carbon atoms transfer all the carbons (groups of two) to acetyl-SCoA after repeated number of trips thru the β-oxidation spiral. Additional steps are required for fatty acids with an odd number of carbons or for those FA with double bonds. All fatty acid carbons are ultimately released for further oxidation into the citric acid cycle [CAC]. ► Each cycle of the spiral generates 1 NADH and 1 FADH 2 . ► Beta-oxidation pathway produces 1 NADH and 1 FADH 2 or ~ 4 ATPs per cycle . ► So: Each Acetyl-SCoA produces 3 NADH, 1 FADH 2 and 1 ATP or 10 ATPs per acetyl-SCoA . 2. Be able to calculate the number of ATP molecules made via Beta-oxidation from a given fatty acid (like we did for palmitic acid in class). (The number of carbons in the fatty acid will be given to you, so don’t memorize the structure of any fatty acids.). The total energy yield is 78 ATP per lauric acid. ► Lauric acid, CH 3 (CH 2 ) 10 COOH, has 12 carbons. ► After initial activation (- 2 ATP), a total of five β-oxidations will be required to degrade lauric acid into 6 Acetyl-SCoA molecules: From CAC : 12 C atoms/2 = 6 Acetyl-SCoAs 6 x 10 ATP = + 60 ATP. From 5 β -oxidations : 5 x ATPs = 20 ATPs Total: -2 ATP + 60 ATP + 20 ATP = 78 ATPs 3. Be able to name the ketone bodies produced in the liver and know under what conditions the liver will synthesis these molecules; Be able to define ketogenesis. When there is too much acetyl-SCoA produced from lipid metabolism for the citric acid cycle to process, the energy is not lost, but is recovered by converting Acetyl- SCoA to ketone bodies (in liver). Ketogenesis:
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This test prep was uploaded on 04/19/2008 for the course CHEM 1530 taught by Professor Davis during the Spring '08 term at Western Michigan.

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Study Guide Exam 4 - 1 CHEM 1530 Exam#4 Study Guide(Chap 26...

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