ctively respiring bacterial culture is supplied with acetyl-CoA labeled on the methyl carbon with carbon- 14 (carbon-14 is radioactive). Shortly after adding the label the citric acid intermediates are isolated and the position of the carbon-14 atom is determined. 12A Where is the carbon-14 label on oxaloacetate after two turns of the citric acid cycle? Consider only the initial incorporation of carbon-14 in the first pass of labeled pyruvate through the citric acid cycle. draw the relevant structures that show how pyruvate is transformed to alpha-ketoglutarate. No mechanisms are required, but provide balanced equations. You do not need to draw the structures of cofactors]
ctively respiring bacterial culture is supplied with acetyl-CoA labeled on the methyl carbon with carbon- 14 (carbon-14 is radioactive). Shortly after adding the label the citric acid intermediates are isolated and the position of the carbon-14 atom is determined. 12A Where is the carbon-14 label on oxaloacetate after two turns of the citric acid cycle? Consider only the initial incorporation of carbon-14 in the first pass of labeled pyruvate through the citric acid cycle. draw the relevant structures that show how pyruvate is transformed to alpha-ketoglutarate. No mechanisms are required, but provide balanced equations. You do not need to draw the structures of cofactors]
Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
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![### Citric Acid Cycle Tracing: Carbon-14 Labeling
**Question #12:**
An actively respiring bacterial culture is supplied with acetyl-CoA labeled on the methyl carbon with carbon-14 (carbon-14 is radioactive). Shortly after adding the label, the citric acid intermediates are isolated, and the position of the carbon-14 atom is determined.
**12A:**
Where is the carbon-14 label on oxaloacetate after two turns of the citric acid cycle? Consider only the initial incorporation of carbon-14 in the first pass of labeled pyruvate through the citric acid cycle. [Name redacted] draw the relevant structures that show how pyruvate is transformed to alpha-ketoglutarate. No mechanisms are required, but provide balanced equations. [You do not need to draw the structures of cofactors]
**12B:**
Suppose both of the acetyl-CoA acetate carbons were carbon-14 labeled. When does the first decarboxylation producing a radioactive 14-CO₂ occur?
### Explanations:
In order to track the carbon-14 label, it is crucial to follow the incorporation of labeled acetyl-CoA into the citric acid cycle, also known as the Krebs cycle or TCA cycle. Initially, acetyl-CoA combines with oxaloacetate to form citrate. Through a series of biochemical transformations involving isomerization and redox reactions, carbon atoms are systematically removed and eventually regenerated to maintain a cyclic nature.
For part A, we must visualize and tabulate the steps to the ultimate return of the labeled carbon in oxaloacetate, while part B requires identifying the reaction where the labeled carbons are first released as CO₂.
By studying these steps, students can understand isotopic labeling and its role in elucidating metabolic pathways, thus reinforcing the dynamics of cellular respiration and intermediary metabolism.
### Educational Value:
This exercise is suitable for biochemistry students learning about metabolic tracing techniques and intricate details of the citric acid cycle's role in cellular respiration.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F2d95edf5-a7eb-463b-b7f4-ca02808af034%2Fd2f41594-d146-4ffb-8fb1-a39c91862251%2F2x9ogzp_processed.jpeg&w=3840&q=75)
Transcribed Image Text:### Citric Acid Cycle Tracing: Carbon-14 Labeling
**Question #12:**
An actively respiring bacterial culture is supplied with acetyl-CoA labeled on the methyl carbon with carbon-14 (carbon-14 is radioactive). Shortly after adding the label, the citric acid intermediates are isolated, and the position of the carbon-14 atom is determined.
**12A:**
Where is the carbon-14 label on oxaloacetate after two turns of the citric acid cycle? Consider only the initial incorporation of carbon-14 in the first pass of labeled pyruvate through the citric acid cycle. [Name redacted] draw the relevant structures that show how pyruvate is transformed to alpha-ketoglutarate. No mechanisms are required, but provide balanced equations. [You do not need to draw the structures of cofactors]
**12B:**
Suppose both of the acetyl-CoA acetate carbons were carbon-14 labeled. When does the first decarboxylation producing a radioactive 14-CO₂ occur?
### Explanations:
In order to track the carbon-14 label, it is crucial to follow the incorporation of labeled acetyl-CoA into the citric acid cycle, also known as the Krebs cycle or TCA cycle. Initially, acetyl-CoA combines with oxaloacetate to form citrate. Through a series of biochemical transformations involving isomerization and redox reactions, carbon atoms are systematically removed and eventually regenerated to maintain a cyclic nature.
For part A, we must visualize and tabulate the steps to the ultimate return of the labeled carbon in oxaloacetate, while part B requires identifying the reaction where the labeled carbons are first released as CO₂.
By studying these steps, students can understand isotopic labeling and its role in elucidating metabolic pathways, thus reinforcing the dynamics of cellular respiration and intermediary metabolism.
### Educational Value:
This exercise is suitable for biochemistry students learning about metabolic tracing techniques and intricate details of the citric acid cycle's role in cellular respiration.
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