Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 19: Problem 11

Describe the labeling pattern that would result if \(^{14} \mathrm{CO}_{2}\) were incorporated into the TCA cycle via the pyruvate carboxylase reaction.

Short Answer

Expert verified
The labeling pattern that would result if \(^{14} \mathrm{CO}_{2}\) were incorporated into the TCA cycle via the pyruvate carboxylase reaction would be that the \(^{14}CO_{2}\) is incorporated into the second carbon position of oxaloacetate. Then, during the TCA cycle, it would be released during the decarboxylation steps.

Step by step solution

01

Understand the Pyruvate Carboxylase Reaction

Pyruvate carboxylase catalyzes the carboxylation of pyruvate to form oxaloacetate. This reaction is an anaplerotic reaction, meaning it replenishes the TCA cycle with intermediates that have been siphoned off for biosynthesis. During this biochemical step \(^{14}CO_{2}\) can be incorporated in this reaction with the pyruvate to form oxaloacetate, and the incorporated \(CO_{2}\) will become one of the carbons in oxaloacetate.
02

Understand the TCA Cycle with Oxaloacetate

The TCA cycle, also known as Krebs or citric acid cycle, begins with the condensation of Acetyl CoA with the 4-carbon molecule oxaloacetate to form a 6-carbon citrate. This citrate, because it is derived from oxaloacetate, will contain the \(^{14}CO_{2}\) labeled carbon in its structure.
03

Determine the Labeling Pattern

Following the progression of this labeled carbon through one turn of the TCA cycle, it ends up in the second carbon position of oxaloacetate, which can be decarboxylated to yield a \(^{14}CO_{2}\) molecule. Therefore, as the TCA cycle continues, the \(^{14}CO_{2}\) would be released during the decarboxylation steps, showing a 'labeling' pattern where the \(^{14}CO_{2}\) is produced.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

(Integrates with Chapter 3 .) Aconitase catalyzes the citric acid cycle reaction: Citrate \(\rightleftharpoons\) isocitrate The standard free energy change, \(\Delta G^{\circ \prime}\), for this reaction is +6.7 \(\mathrm{kJ} / \mathrm{mol}\). However, the observed free energy change \((\Delta G)\) for this reaction in pig heart mitochondria is \(+0.8 \mathrm{kJ} / \mathrm{mol}\). What is the ratio of [isocitrate]/[citrate] in these mitochondria? If [isocitrate] = \(0.03 \mathrm{m} M,\) what is [citrate]?

In addition to fluoroacetate, consider whether other analogs of TCA cycle metabolites or intermediates might be introduced to inhibit other, specific reactions of the cycle. Explain your reasoning.

The malate synthase reaction, which produces malate from acetylCoA and glyoxylate in the glyoxylate pathway, involves chemistry similar to the citrate synthase reaction. Write a mechanism for the malate synthase reaction and explain the role of CoA in this reaction.

In most cells, fatty acids are synthesized from acetate units in the cytosol. However, the primary source of acetate units is the TCA cycle in mitochondria, and acetate cannot be transported directly from the mitochondria to the cytosol. Cells solve this problem by exporting citrate from the mitochondria and then converting citrate to acetate and oxaloacetate. Then, because cells cannot transport oxaloacetate into mitochondria directly, they must convert it to malate or pyruvate, both of which can be taken up by mitochondria. Draw a complete pathway for citrate export, conversion of citrate to malate and pyruvate, and import of malate and pyruvate by mitochondria. a. Which of the reactions in this cycle might require energy input? b. What would be the most likely source of this energy? c. Do you recognize any of the enzyme reactions in this cycle? d. What coenzymes might be required to run this cycle?

In a tissue where the TCA cycle has been inhibited by fluoroacetate, what difference in the concentration of each TCA cycle metabolite would you expect, compared with a normal, uninhibited tissue?
See all solutions

Recommended explanations on Chemistry Textbooks

Kinetics

Read Explanation

Inorganic Chemistry

Read Explanation

Physical Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Organic Chemistry

Read Explanation

Making Measurements

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free