Chapter 13, Problem 13.98EP

(a)

Interpretation Introduction

Interpretation: To indicate whether the statement “the initial reactant for the PPP is ribose” relating to the pentose phosphate pathway (PPP) is true or false.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, $\text{ribose 5}-\text{phosphate}$, and other sugar phosphates are produced from $\text{glucose 6}-\text{phosphate}$.

Pentose phosphate pathway is a two-stage metabolic pathway. The first stage of phosphate pentose pathway is an oxidative stage and the second stage is a non-oxidative stage.

A reactant is defined as the substance that is initially present in the chemical reaction and gets consumed to form a new substance.

(b)

Interpretation Introduction

Interpretation: To indicate whether the statement “the final products of the PPP include two glycolysis intermediates” relating to the pentose phosphate pathway (PPP) is true or false.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, $\text{ribose 5}-\text{phosphate}$, and other sugar phosphates are produced from $\text{glucose 6}-\text{phosphate}$.

Pentose phosphate pathway is a two-stage metabolic pathway. The first stage of phosphate pentose pathway is an oxidative stage and the second stage is a non-oxidative stage.

In the glycolysis metabolic pathway, a glucose molecule is converted to two pyruvate molecules. ATP molecules and NADH-reduced coenzymes are produced along with pyruvate.

An intermediate is defined as the transient species that is formed from the reactants in the preceding step and gets consumed in the subsequent steps to generate the products. An intermediate is formed within a multi-step reaction.

(c)

Interpretation Introduction

Interpretation: To indicate whether the statement “$\text{ribose 5}-\text{phosphate}$ is a product of the first stage of the PPP” relating to the pentose phosphate pathway (PPP) is true or false.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, $\text{ribose 5}-\text{phosphate}$, and other sugar phosphates are produced from $\text{glucose 6}-\text{phosphate}$.

Pentose phosphate pathway is a two-stage metabolic pathway. The first stage of phosphate pentose pathway is an oxidative stage and the second stage is a non-oxidative stage.

A product is defined as the substance that is formed after the completion of a chemical reaction.

(d)

Interpretation Introduction

Interpretation: To indicate whether the statement “in the first step of the second stage of the PPP $\text{ribulose 5}-\text{phosphate}$ is converted to $\text{ribose 5}-\text{phosphate}$” relating to the pentose phosphate pathway (PPP) is true or false.

Concept introduction: The pentose phosphate pathway is defined as the metabolic pathway in which NADPH, $\text{ribose 5}-\text{phosphate}$, and other sugar phosphates are produced from $\text{glucose 6}-\text{phosphate}$.

Pentose phosphate pathway is a two-stage metabolic pathway. The first stage of phosphate pentose pathway is an oxidative stage and the second stage is a non-oxidative stage.