View answer: ?Answer true or false to the following questions to assess your general

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems. Fatty acids are metabolized through the process of ????-oxidation. (21.5)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems. NAD?, NADH, FAD, and FADH? are coenzymes that undergo oxidation and reduction during metabolism. (21.1)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems. NAD? acts to oxidize both hydroxyl and carbonyl groups. (21.2)

How many moles of ethanol are produced per mole of sucrose through the reactions of glycolysis and alcoholic fermentation? How many moles of CO? are produced?

Ethanol is oxidized in the liver to acetate ion by NAD? (a) Write a balanced equation for this oxidation. (b) Do you expect the pH of blood plasma to increase, decrease, or remain the same as a result of the metabolism of a significant amount of ethanol?

Which carbons of glucose end up in CO? as a result of alcoholic fermentation?

Name three coenzymes that are necessary for the ????-oxidation of fatty acids. From what vitamin is each derived?

We have examined ????-oxidation of saturated fatty acids, such as palmitic acid and stearic acid. Oleic acid, an unsaturated fatty acid, is also a common component of dietary fats and oils. This unsaturated fatty acid is degraded by ????-oxidation, but, at one stage in its degradation, requires an additional enzyme named enoyl-CoA isomerase. Why is this enzyme necessary, and what isomerization does it catalyze? (Hint: Consider both the configuration of the carbon–carbon double bond in oleic acid and its position in the carbon chain.)

Which steps in the citric acid cycle involve (a) The formation of new carbon–carbon bonds (b) The breaking of carbon–carbon bonds (c) Oxidation by NAD? (d) Oxidation by FAD (e) Decarboxylation (f) The creation of new stereocenters

Review the oxidation reactions of glycolysis, boxidation, and the citric acid cycle, and compare the types of functional groups oxidized by NAD? with those oxidized by FAD.

The respiratory quotient (RQ), used in studies of energy metabolism and exercise physiology, is defined as the ratio of the volume of carbon dioxide produced to the volume of oxygen used: (a) Show that RQ for glucose is 1.00. (Hint: Look at the balanced equation for the complete oxidation of glucose to carbon dioxide and water.) (b) Calculate RQ for triolein, a triglyceride with the molecular formula C??H???O?. (c) For an individual on a normal diet, RQ is approximately 0.85. Would this value increase or decrease if ethanol were to supply an appreciable portion of the person’s caloric needs?

Acetoacetate, ????-hydroxybutyrate, and acetone are commonly referred to within the health sciences as “ketone bodies,” in spite of the fact that one of them is not a ketone at all. All are products of human metabolism and are always present in blood plasma. Most tissues (with the notable exception of the brain) have the enzyme systems necessary to use ketone bodies as energy sources. Ketone bodies are synthesized by the enzyme-catalyzed reactions shown below. Describe the type of reaction involved in each step.

A connecting point between anaerobic glycolysis and ????-oxidation is the formation of acetyl-CoA. Which carbon atoms of glucose appear as methyl groups of acetyl-CoA? Which carbon atoms of palmitic acid appear as methyl groups of acetyl-CoA?

Which of the steps in the following biochemical pathways use molecular oxygen as the oxidizing agent? (a) Glycolysis (b) ????-Oxidation (c) The citric acid cycle

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems. An end product of glycolysis is pyruvate. (21.2–21.4)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems. The starting point of the citric acid cycle involves acetyl CoA, which can be formed from carbohydrates, triglycerides, or proteins. (21.6)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems. Lactate fermentation allows pyruvate to be metabolized under aerobic conditions. (21.4)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems All carbohydrates are directly metabolized through the process of glycolysis. (21.1–21.4)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems Keto–enol tautomerism is an important reaction in glycolysis. (21.3)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems Coenzyme A is used in metabolism to store and transfer hydroxyl groups. (21.1)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems Coenzyme A contains a terminal - OH group, which forms a new bond to acetyl groups in the degradation of monosaccharides, fatty acids, glycerol, and amino acids. (21.1, 21.4–21.6)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems Alcoholic fermentation is one possible means of pyruvate metabolism in humans. (21.4)

Answer true or false to the following questions to assess your general knowledge of the concepts in this chapter. If you have difficulty with any of them, you should review the appropriate section in the chapter (shown in parentheses) before attempting the more challenging end-of-chapter problems ATP, ADP, and AMP are involved in the storage and transfer of adenine groups. (21.1)

In many enzyme-catalyzed reactions, a group on the enzyme functions as a proton donor. List several amino acid side chains that could function as proton donors.

In many other enzyme-catalyzed reactions, a group on the enzyme surface functions as a proton acceptor. List several amino acid side chains that might function as proton acceptors.

Name one coenzyme required for glycolysis. From what vitamin is the coenzyme derived?

Number the carbons of glucose 1 through 6. Which carbons of glucose become the carboxyl groups of the two pyruvates?

How many moles of lactate are produced from 3 moles of glucose?

Although glucose is the principal source of carbohydrates for glycolysis, fructose and galactose are also metabolized for energy. (a) What is the main dietary source of fructose? Of galactose? (b) Propose a series of reactions by which fructose might enter glycolysis. (c) Propose a series of reactions by which galactose might enter glycolysis.

Glycerol that is derived from the hydrolysis of triglycerides and phospholipids is also metabolized for energy. Propose a series of reactions by which the carbon skeleton of glycerol might enter glycolysis and be oxidized to pyruvate.

Write a mechanism to show the role of NADH in the reduction of acetaldehyde to ethanol.

When pyruvate is reduced to lactate by NADH, two hydrogens are added to pyruvate: one to the carbonyl carbon, the other to the carbonyl oxygen. Which of these hydrogens is derived from NADH?

Why is glycolysis called an anaerobic pathway?

Which steps in glycolysis require ATP? Which steps produce ATP?

Write structural formulas for palmitic, oleic, and stearic acids, the three most abundant fatty acids.

A fatty acid must be activated before it can be metabolized in cells. Write a balanced equation for the activation of palmitic acid.

What is the main function of the citric acid cycle?

What does it mean to say that the citric acid cycle is catalytic—that is, that it does not produce any new compounds?

Compare biological (enzyme-catalyzed) reactions with laboratory reactions in terms of (a) Efficiency of yields (b) Regiochemical outcome of products (c) Stereochemical outcome of products

Comment on the importance of stereochemistry in the synthesis of new drugs.

Of the functional groups that we have studied, which are affected by the acidity of biological environments (biological pH)?

Can you think of any aspect of your day-to-day life that does not involve or is not affected by organic chemistry? Explain.