Consider the production of lauric acid (12:0) in the fruit of a coconut tree. The source of the carbon is glucose that has been produced in other parts of the plant (a) How many molecules of glucose are needed to produce the acetyl CoA for one molecule of lauric acid? (b) How many NADH are produced in the conversion of glucose to acetyl CoA? (c) Let's assume that the NADH is converted to NADPH. Is there sufficient NADPH for synthesis of lauric acid? If yes, what amount of NADH is left over? If no, what amount of NADPH must be supplied by another pathway? (d) How many ATP are produced in the conversion of glucose to acetyl CoA? (e) The acetyl CoA is produced in the mitochondria and must be transported to the cytosol. Is there sufficient ATP for synthesis of lauric acid? If yes, what amount of ATP is left over? If no, what amount of ATP must be supplied by another pathway?

Consider the production of lauric acid (12:0) in the fruit of a coconut tree. The source of the carbon is glucose that has been produced in other parts of the plant (a) How many molecules of glucose are needed to produce the acetyl CoA for one molecule of lauric acid? (b) How many NADH are produced in the conversion of glucose to acetyl CoA? (c) Let's assume that the NADH is converted to NADPH. Is there sufficient NADPH for synthesis of lauric acid? If yes, what amount of NADH is left over? If no, what amount of NADPH must be supplied by another pathway? (d) How many ATP are produced in the conversion of glucose to acetyl CoA? (e) The acetyl CoA is produced in the mitochondria and must be transported to the cytosol. Is there sufficient ATP for synthesis of lauric acid? If yes, what amount of ATP is left over? If no, what amount of ATP must be supplied by another pathway?

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter19: The Tricarboxylic Acid Cycle

Section: Chapter Questions

Problem 22P: Study Figure 19.18 and decide which of the following statements is false. Pyruvate dehydrogenase is...

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The CO2 produced in one round of the citric acid cycle does not originate in the acetyl carbons that entered that round. (a) How many rounds are required before 14CO2 is released if acetyl-CoA is labeled at its methyl group? (b) If acetyl-CoA is labeled with 14C at its carbonyl carbon, how many rounds of the cycle are required before 14CO2 is released?
Which of the following statements about the pentose phosphate pathway (PPP) is true? (A) The purpose of the pentose phosphate pathway is to produce NADH for use in anabolic pathways and ribose 6-phosphate for nucleotide synthesis.(B) The oxidative arm of the PPP produces (2) NADPH per glucose 6-phosphate that enters the pathway. (C) Phosphopentose isomerase converts the ribose 5-phosphate made in the oxidative arm of the PPP into ribulose 5-phosphate that is used to form the ribose sugar of nucleotides.(D) The non-oxidative arm of the PPP interconverts between ribose 5-phosphate and a variety of intermediates of b-oxidation. (E) One of the functions of the PPP is to provide NADPH that inhibits glutathione reductase so that it cannot oxidatively damage RBCs.
Consider an acetyl CoA that enters the TCA cycle. Let’s call this cycle “Cycle 1.” Let’s say you put a radiolabel on the carbonyl carbon of acetyl CoA that will allow us to track this carbon through the TCA cycle. Now, trace its path through the TCA cycle and answer the following questions: (a) Does the carbonyl carbon of Acetyl CoA come out as CO2 in Cycle 1? (b) If your answer to (a) was No, in which cycle does it come out as CO2 (Cycle 2, 3, 4 …)
How many acetyl CoA molecules are produced in one cycle of beta oxidation? How many cycles would it take to catabolize a stearic acid molecule (a fatty acid, [18:0]) into acetyl Co A units? a)How many acetyl CoA molecules would be produced? b) How many reduced nucleotides would be produced? c) If a molecule of glucose produces a net 32 ATP when completely catabolized, which do you think will produce more energy, one molecule of glucose or one molecule of stearic acid? Justify your answer.
(c) (1 ) Fluoroacetate, prepared commercially for rodent control, is also produced by a South Afri- can plant. After entering a cell, fluoroacetate is converted to fluoroacetyl-CoA in a reaction catalyzed by the enzyme acetate thiokinase: F-CH2COO¯ + COA-SH + ATP F-CH2CO-SCOA + AMP + PPj The toxic effect of fluoroacetate was studied in an experiment using intact isolated rat heart. After the heart was perfused with 0.22 mM fluoroacetate, the measured rate of glucose uptake and glycolysis decreased, and glucose 6-phosphate and fructose 6-phosphate accumulated. Examination of the cit- ric acid cycle intermediates revealed that their concentrations were below normal, except for citrate, with a concentration 10-fold higher than normal. Where did the block in the citric acid cycle occur? What caused citrate to accumulate and the other cycle intermediates to be depleted? Explain. Why does it block the citric acid cycle? Fluoroacetyl-CoA is enzymatically transformed in the citric acid cycle.…
D) Carbohydrate catabolism involves substrate-level phosphorylation. E) My answer is not here 27. The adduct acetoacetyl-acyl carrier protein is formed as an intermediate during fatty acid biosynthesis. The CO2 used to synthesize malonyl-S-CoA is lost. Would this help make the reaction more or less energetically favorable? A) Loss of CO2 increases entropy (AS) and therefore decreases the favorability of the reaction (AG). B) Loss of CO2 has no effect on entropy (AS) and therefore does not affect the favorability of the reaction (AG). C) Loss of CO2 increases entropy (AS) and therefore increases the favorability of the reaction (AG). D) Loss of CO2 decreases entropy (AS) and therefore decreases the favorability of the reaction (AG). E) Loss of CO2 decreases entropy (AS) and therefore increases the favorability of the reaction (AG).
The immediate precursor to acetyl–CoA from glycolysis is pyruvate.a) Write the pathway (not the mechanism) for the series of steps for this conversion. Includestructures for all coenzymes and reactants for each step.b) Discuss the mechanistic advantages offered by this multienzyme complex. Be specific and giveexamples.c) The last step of the reaction, catalyzed by enzyme 3, includes three coenzymes and oxidation.Write the mechanism for this enzyme.
Consider the fatty acids: (a) Arachidic acid (C20H40O2); molar mass = 312.5 g/mol) (b) Palmitoleic acid(C16H30O2); molar mass = 256.4 g/mol). i. How many cycles of β -oxidation are needed for complete oxidation?ii. How many molecules of acetyl CoA are formed from its complete catabolism?iii. Calculate the number of molecules (moles) of ATP formed (net) by the completecatabolism of each fatty acid (show your calculation).iv. Calculate number of moles of ATP formed per gram of each fatty acid metabolized.
The citric acid cycle is a critical sequence of reactions for energy production, which take place in the matrix of the mitochondria. The reaction cycle requires materials from the cytosol to be converted into acetyl CoA, which represents the starting point of a new cycle. Which of the following statements about acetyl CoA is true? (a) Acetyl CoA is recycled at the end of every cycle. (b) Oxaloacetate is attached to acetyl CoA to feed the citric acid cycle. (c) Triacylglycerol molecules are transported into the mitochondrial matrix and cleaved by lipases to produce acetyl CoA. (d) Oxaloacetate is converted directly into acetyl CoA to feed the citric acid cycle
In some tissues, glucose 6-phosphate is oxidized to pentose phosphates by the pentose phosphate pathway. a) Which tissues prefer this pathway and why? Explain in detail. b) Due to the fact that glucose 6-phosphate is also an intermediate for the glycolysis pathway, the regulation of glycolysis and pentose phosphate pathway is very important. NADPH plays a crucial role in partitioning of glucose 6-phosphate between glycolysis and the pentose phosphate pathway. Explain this role of NADPH in detail.
How many molecules of acetyl CoA, FADH2, and NADH are produced in the catabolism of a molecule of arachidonic acid, an 20-carbon carboxylic acid? How many times does the spiral reaction sequence occur
Decylic acid is a saturated fatty acid that occurs naturally in coconut oil and palm kernel oil. Calculate the net ATP yield when decylic acid undergoes complete B oxidation. The formula of decylic acid is shown below: (Given: The oxidation of one NADH yields 2.5 ATP; the oxidation of one FADH2 yields 1.5 ATP; and the oxidation of one acetyl CoA yields 10 ATP.) O 50 ATP O 52 ATP 66 ATP OH O 64 ATP