Why is it more accurate to call the pathway that converts acetyl-CoA to COA + 2 CO₂ the citrate cycle, rather than the tricarboxylic acid cycle (TCA), or simply the citric acid cycle? Because tricarboxylic acid (TCA) could also be confused with trichloroacetic acid, which is confusing Because Edwin Krebs thought that the carboxyl groups of citric acid had a pK₂ of 9 instead of ~5. Because the primary product of reaction 1 in cells is citrate, which is a base not an acid at pH 7. Because Krebs cycle, TCA, and citric acid cycle are three different metabolic pathways. Because the primary product of reaction 1 in cells is isocitrate, which is a base not an acid at pH 4.

Why is it more accurate to call the pathway that converts acetyl-CoA to COA + 2 CO₂ the citrate cycle, rather than the tricarboxylic acid cycle (TCA), or simply the citric acid cycle? Because tricarboxylic acid (TCA) could also be confused with trichloroacetic acid, which is confusing Because Edwin Krebs thought that the carboxyl groups of citric acid had a pK₂ of 9 instead of ~5. Because the primary product of reaction 1 in cells is citrate, which is a base not an acid at pH 7. Because Krebs cycle, TCA, and citric acid cycle are three different metabolic pathways. Because the primary product of reaction 1 in cells is isocitrate, which is a base not an acid at pH 4.

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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Study Figure 19.18 and decide which of the following statements is false. Pyruvate dehydrogenase is inhibited byÂ· NIADH. Pyruvate dehydrogenase is inhibited by AÎ¤Î¡. Citrate synthase is inhibited by NADH. Succinyl-CoA activates citrate synthase. Acetyl-CoA activates pyruvate carboxylase.
A fatty acid (a long straight-chain carboxylic acid with an even number of carbons) is metabolized to acetyl- CoA, which can then enter the citric acid cycle to be further metabolized (Section 24.9). A fatty acid with anodd number of carbons is metabolized to acetyl-CoA and one equivalent of propionyl-CoA. Propionyl-CoA cannot enter the citric acid cycle. Two coenzyme-requiring enzymes are needed to convert it to succinyl-CoA, acompound that can enter the citric acid cycle. Write the two enzyme-catalyzed reactions and include the names of the required coenzymes.
Which of the following statements is/are TRUE for the Krebs' cycle? Reaction 1: condensation of acetyl-CoA and oxaloacetate; produces H20. Reaction 3: oxidation of isocitrate to a-ketoglutarate; produces NADH and CO2. Reaction 6: oxidation of succinate to fumarate; produces FADH2 and CO2 Reaction 5: hydrolysis of succinyl-CoA to succinate; produces ATP.
The citric acid cycle is shown. The methyl carbon in acetyl CoA is labeled with C14C14 (shown in red). Identify which of the carbons in each intermediate will be labeled in the first round of the cycle by selecting the indicated carbon(s). Each question has multiple options, please choose more than one. Which carbon(s) in α‑ketoglutarate will contain C14? 1 2 3 4 5 Which carbon(s) in succinyl‑CoA will contain C14? 1 2 3 4 Which carbon(s) in succinate will contain C14? 1 2 3 4 Which carbon(s) in fumarate will contain C14? 1 2 3 4 Which carbon(s) in malate will contain C14? 1 2 3 4 Which carbon(s) in oxaloacetate will contain C14? 1 2 3 4
The citric acid cycle is shown. The methyl carbon in acetyl CoA is labeled with C14C14 (shown in red). Identify which of the carbons in each intermediate will be labeled in the first round of the cycle by selecting the indicated carbon(s). Each question has multiple options, answering with only one option is incorrect. Which carbon(s) in α‑ketoglutarate will contain C14? 1 2 3 4 5 Which carbon(s) in succinyl‑CoA will contain C14? 1 2 3 4 Which carbon(s) in succinate will contain C14? 1 2 3 4 Which carbon(s) in fumarate will contain C14? 1 2 3 4 Which carbon(s) in malate will contain C14? 1 2 3 4 Which carbon(s) in oxaloacetate will contain C14? 1 2 3 4
coo- 21 CH2 316 НО-С-СОО- HOC COO- 4 CH2 | 5, °coo-
Malate synthase, an enzyme of the glyoxylate cycle, catalyzes the condensa- tion of glyoxylate with acetyl-CoA. Which enzyme of the citric acid cycle carries out a similar reaction? Would you expect the binding of glyoxylate and acetyl-CoA to malate synthase to be sequential? Why?
There are eight chemical reactions that occur in the citric acid cycle process. The reactions of the citric acid cycle are shown in the figure below. acetyl-coenzyme A 0 CH₂-C-CoA HO-CH Reaction 7 O malate CH₂ CH || CH fumarate FADH₂ Reaction 6 FAD H+ + NADH NAD+ 1,0 H₂C CH₂ CH₂ Reaction 8 succinate ADP 0=C GTP CH₂ oxaloacetate Reaction 5 H-COA GDP ATP H₂O Reaction 1 C Reactions of the Citric Acid Cycle CH₂ CH₂ H-COA 0=C 1 CoA succinyl-CoA H+ HO-C Reaction CO₂ с CH₂ NADH CH₂ citrate Reaction 2 H-COA Reaction 3 CO₂ I CH₂ T CH₂ 0=C NAD+ HO–CH a-ketoglutarate CH, CH isocitrate NAD+ H+ + NADH In chapters 9 and 10, you were introduced to several classes of organic reactions. These classes include esterification, decarboxylation, hydration reactions, dehydration of alcohols, oxidation of alcohols, oxidation of aldehydes, reduction of aldehydes, and reduction of ketones. Find at least one of these reaction classes in the citric acid cycle. List the reaction number and the reaction. Write a…
The citrate cycle is a metabolic engine generating [ Select: "carbon monoxide", "NAD, FAD and GDP", "carbon dioxide, NADH, FADH, and GTP"] from the fuel [ Select : "triglycerides", "acetyl-CoA"]. It is considered a cycle since all components must be maintained beginning with the addition of the two carbons from acetyl-CoA to form [ Select ] ["succinate", "citrate"] from [ Select ]["fumarate", "oxaloacetate"]. The citrate cycle depends on the presence of oxygen since [ Select ]["oxygen is directly required in the citrate cycle", "oxygen is required for NADH and FADH2 oxidation, and their accumulation in the absence of electron transport results in feedback inhibition of the citrate cycle"] .
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
The citric acid cycle converts each acetyl-CoA to [1/2/3/4] molecules of CO2. This pathway is considered [catabolic/anabolic] because it breaks down acetyl-CoA into smaller molecules and [catabolic/anabolic] because the intermediates are building blocks for other metabolites in the cell. The citric acid cycle produces [1/2/3] NADH and [1/2/3] FADH2 for every acetyl-CoA consumed. help fill in the blanks
Most fatty acids have an even number of carbons and, therefore, are completely metabolized to acetyl-CoA. A fatty acid with an odd number of carbonsis metabolized to acetyl-CoA and one equivalent of propionyl-CoA. The following two reactions convert propionyl-CoA into succinyl-CoA, a citric acidcycle intermediate, so it can be further metabolized. Each of the reactions requires a coenzyme. Identify the coenzyme for each step. From what vitaminsare the coenzymes derived? (Hint: see Chapter 23.) COO− COO−CH2CH2methylmalonyl-CoA succinyl-CoA CH3CH2 SCoA