Which of the following is not a product of glycolysis?
ATP
glucose
pyruvic acid
NADH
The Correct Answer and Explanation is:
The correct answer is glucose.
Explanation:
Glycolysis is the first stage of cellular respiration, where glucose is broken down into smaller molecules to generate energy. This process occurs in the cytoplasm of the cell and involves a series of enzyme-catalyzed reactions that convert glucose into pyruvic acid (also known as pyruvate), producing energy in the form of ATP and reducing equivalents in the form of NADH.
Here’s a breakdown of the products of glycolysis:
- ATP: Glycolysis produces a net gain of 2 ATP molecules. While 2 ATP molecules are consumed in the initial steps of glycolysis, 4 ATP molecules are produced in the later stages, resulting in a net gain of 2 ATP molecules. This occurs through substrate-level phosphorylation, a process where a phosphate group is directly transferred to ADP from a high-energy substrate molecule.
- Pyruvic acid (Pyruvate): Pyruvic acid is the final product of glycolysis. One glucose molecule (a six-carbon sugar) is broken down into two molecules of pyruvate (each with three carbons). This happens through a series of steps that include oxidation reactions, producing energy in the form of NADH.
- NADH: In glycolysis, NAD+ is reduced to NADH as glucose is oxidized. This is an essential step for the cell, as NADH carries high-energy electrons to the electron transport chain (in later stages of cellular respiration) to help generate additional ATP.
- Glucose: Glucose is not a product of glycolysis; rather, it is the starting substrate. Glycolysis begins with the molecule of glucose, which is broken down into pyruvic acid, ATP, and NADH. Therefore, glucose is consumed in the process of glycolysis, not produced by it.
In summary, glucose is the starting material for glycolysis, while ATP, pyruvic acid, and NADH are the key products of the process.