Ch.18 Metabolic Pathways and ATP Production

Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition

Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook

Timberlake 13th Edition

Ch.18 Metabolic Pathways and ATP Production

Problem 28c

Chapter 18, Problem 28c

How many ATP or NADH are produced (or required) in each of the following steps in glycolysis?
c. phosphoenolpyruvate to pyruvate

Verified step by step guidance

Step 1: Understand the context of the reaction. The conversion of phosphoenolpyruvate (PEP) to pyruvate is the final step in glycolysis, catalyzed by the enzyme pyruvate kinase.

Step 2: Recall that this step is a substrate-level phosphorylation reaction. During this process, a phosphate group from phosphoenolpyruvate is transferred to ADP to form ATP.

Step 3: Write the chemical equation for the reaction:

phosphoenolpyruvate + ADP + H

⁺ → pyruvate + ATP.

Step 4: Note that for each molecule of phosphoenolpyruvate converted to pyruvate, one molecule of ATP is produced. This is a net gain of ATP in glycolysis.

Step 5: Summarize the result: The conversion of phosphoenolpyruvate to pyruvate produces 1 ATP per molecule of phosphoenolpyruvate.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Glycolysis

Glycolysis is a metabolic pathway that converts glucose into pyruvate, producing energy in the form of ATP and NADH. It occurs in the cytoplasm of cells and consists of ten enzymatic reactions, divided into two phases: the energy investment phase and the energy payoff phase. Understanding glycolysis is essential for analyzing energy production in cellular respiration.

Phosphoenolpyruvate (PEP)

Phosphoenolpyruvate (PEP) is a high-energy intermediate in glycolysis, formed from 2-phosphoglycerate. It plays a crucial role in the final step of glycolysis, where it is converted to pyruvate by the enzyme pyruvate kinase. This reaction is significant because it generates ATP through substrate-level phosphorylation, contributing to the overall energy yield of glycolysis.

ATP and NADH Production

During glycolysis, ATP and NADH are produced through various reactions. Specifically, the conversion of phosphoenolpyruvate to pyruvate generates one ATP molecule via substrate-level phosphorylation. Additionally, glycolysis produces two NADH molecules per glucose molecule, which are crucial for further energy production in aerobic respiration.

How many ATP or NADH are produced (or required) in each of the following steps in glycolysis?c. phosphoenolpyruvate to pyruvate