Concept explainers
(a)
Interpretation:
Whether the citrate shuttle system is used in (1) the β-oxidation pathway, (2) ketogenesis, or (3) lipogenesis has to be determined.
Concept introduction:
Lipogenesis is the process employed for the synthesis of fatty acid. The starting precursor for the synthesis is acetyl CoA. The enzyme employed for the process is fatty acid synthase. It is a multienzyme complex that ties the reaction responsible for the synthesis of fatty acid. The fatty acid is synthesized in two parts. In the first part, there is citrate-malate shuttle system and in the second part, there is an acyclic process to synthesize saturated fatty acid.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acetyl CoA is degraded to acetyl CoA. This pathway is termed as β-oxidation pathway.
Ketogenesis is a
(b)
Interpretation:
Whether acetyl ACP is used in (1) the β-oxidation pathway, (2) ketogenesis, or (3) lipogenesis has to be determined.
Concept introduction:
Lipogenesis is the process employed for the synthesis of fatty acid. The starting precursor for the synthesis is acetyl CoA. The enzyme employed for the process is fatty acid synthase. It is a multienzyme complex that ties the reaction responsible for the synthesis of fatty acid. The fatty acid is synthesized in two parts. In the first part, there is citrate-malate shuttle system and in the second part, there is an acyclic process to synthesize saturated fatty acid.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acetyl CoA is degraded to acetyl CoA. This pathway is termed as β-oxidation pathway.
Ketogenesis is a metabolic process by which ketone bodies are produced by the breakdown of fatty acids and ketogenic amino acids. This metabolic process supplies organs with needed energy under certain circumstances such as starvation. Fatty acid molecules degrade into acetyl CoA which are utilized as reactants in the process of ketogenesis. acetyl CoA undergo the process of condensation twice, followed by chain cleavage and hydrogenation to produce ketone bodies.
(c)
Interpretation:
Whether H2O is used in (1) the β-oxidation pathway, (2) ketogenesis, or (3) lipogenesis has to be determined.
Concept introduction:
Lipogenesis is the process employed for the synthesis of fatty acid. The starting precursor for the synthesis is acetyl CoA. The enzyme employed for the process is fatty acid synthase. It is a multienzyme complex that ties the reaction responsible for the synthesis of fatty acid. The fatty acid is synthesized in two parts. In the first part, there is citrate-malate shuttle system and in the second part, there is an acyclic process to synthesize saturated fatty acid.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acetyl CoA is degraded to acetyl CoA. This pathway is termed as β-oxidation pathway.
Ketogenesis is a metabolic process by which ketone bodies are produced by the breakdown of fatty acids and ketogenic amino acids. This metabolic process supplies organs with needed energy under certain circumstances such as starvation. Fatty acid molecules degrade into acetyl CoA which are utilized as reactants in the process of ketogenesis. acetyl CoA undergo the process of condensation twice, followed by chain cleavage and hydrogenation to produce ketone bodies.
(d)
Interpretation:
Whether H2O is used as a reactant in (1) the β-oxidation pathway, (2) ketogenesis, or (3) lipogenesis has to be determined.
Concept introduction:
Lipogenesis is the process employed for the synthesis of fatty acid. The starting precursor for the synthesis is acetyl CoA. The enzyme employed for the process is fatty acid synthase. It is a multienzyme complex that ties the reaction responsible for the synthesis of fatty acid. The fatty acid is synthesized in two parts. In the first part, there is citrate-malate shuttle system and in the second part, there is an acyclic process to synthesize saturated fatty acid.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acetyl CoA is degraded to acetyl CoA. This pathway is termed as β-oxidation pathway.
Ketogenesis is a metabolic process by which ketone bodies are produced by the breakdown of fatty acids and ketogenic amino acids. This metabolic process supplies organs with needed energy under certain circumstances such as starvation. Fatty acid molecules degrade into acetyl CoA which are utilized as reactants in the process of ketogenesis. acetyl CoA undergo the process of condensation twice, followed by chain cleavage and hydrogenation to produce ketone bodies.
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EBK GENERAL, ORGANIC, AND BIOLOGICAL CH
- Which of the following is the chemical end product of fatty-acids metabolized in the beta-oxidation pathway? Select one: a. Beta-carotine b. Free-radicals c. Lactic acid d. Acetyl-CoA e. Pyruvatearrow_forwardWhich of the following produces the highest number of reducing equivalent molecules per mole of a saturated 10 carbon fatty acid chain in aerobic conditions? A. Oxidation of Malate to Oxaloacetate B. the Electron Transport Chain C. Oxidation of a-Ketoglutarate to Succinyl-COA D. the B-Oxidation "spiral"arrow_forwardThe rate-limiting step in fatty acid synthesis is: a. The reduction of the acetoacetyl group to a ?-hydroxybutyryl group b. Formation of malonyl-CoA from malonate and coenzyme A. c. Condensation of acetyl-CoA and malonyl-CoA. d. The reaction catalyzed by acetyl-CoA carboxylase.arrow_forward
- Which of the following statements about the "central role" of TCA is/are correct? a. Some metabolic intermediates of TCA are used as non-carbohydrate sources for gluconeogenesis. b. β-oxidation of lipids produces acetyl-CoA that can enter TCA. c. All metabolic intermediates in TCA are used in the biosynthesis of amino acids. d. Degraded amino acids are converted to metabolic intermediates of TCA, then to ketone bodies.arrow_forwardFatty acid biosynthesis differs from β-oxidation in that: A. NADP+ is used in biosynthesis but not in β-oxidation. B. Biosynthesis uses malonyl-CoA while β-oxidation does not. C. Biosynthesis occurs in the cytoplasm while β-oxidation occurs in the mitochondria. D. Biosynthesis is a reductive process while β-oxidation is oxidation.arrow_forwardIn the context of fatty acid oxidation to acetyl CoA, indicate whether each of the following substances is involved in (1) fatty acid activation, (2) fatty acid trans-port, or (3) b-oxidation pathway. More than one choice may be correct in a given situation. a. AMp b. FAD c. Acyl CoA d. H2Oarrow_forward
- Five coenzymes are required by a-ketoglutarate dehydrogenase, the enzyme in the citric acid cycle that converts a-ketoglutarate to succinyl-CoA.a. Identify the coenzymes.b. Propose a mechanism for the reaction. A-ketoglutarate dehydrogenase A-ketoglutarate succinyl-CoAOO OO O−O O− −O SCoA + CO2arrow_forwardalpha-ketoglutarate dehydrogenase will do which of the following: Select one: a. Pyruvate is decarboxylated to become acetyl-CoA producing NADH and Carbon dioxide b. Succinate is oxidized to become fumarate forming FADH2 c. Succinyl-CoA becomes Succinate and forms one ATP molecule and Coenzyme A-SH d. Oxaloacetate combines with the acetyl from acetyl-CoA to produce Citric acid(citrate) e. Malate is oxidized to become oxaloacetate forming NADH f. Isocitrate and then decarboxylated and oxidized to produce alpha-ketoglutarate, Carbon dioxide and NADH g. Citrate is rearranged to become Isocitrate h. Fumarate is combined with water to become Malate i. alpha-ketoglutarate is oxidized and decarboxylated to produce Succinyl-CoA, Carbon dioxide and NADHarrow_forwardThe rate limiting and committed step of the pentose phosphate pathway is catalyzed by which of the following enzymes? A. Glucose-6-phosphate dehydrogenase B. Hexokinase C. 6-Phosphogluconate dehydrogenase D. Transketolasearrow_forward
- Which of the following statements is/are TRUE about fatty acid activation before β-oxidation? I. The process consumes energy equivalent to two moles of ATP. II. The fatty acid is activated by ATP to give a fatty acyl-CoA.arrow_forwardWhich of the following reactions correspond to the decarboxylation step during ketone body formation? A. 2 acetyl-CoA → acetoacetyl-CoA B. ß-hydroxybutarate → acetoacetate C. Acetoacetate → acetone D. HMG-CoA → mevalonatearrow_forwardIf glycerol-3-phosphate shuttle is active, calculate the number of ATP produced from the complete oxidation of: a. cerotic acidb. heptadecanoic acidc. palmitoleic acidarrow_forward
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