Chapter 21, Problem 21.20UKC

(a)

Interpretation Introduction

Interpretation:

The exergonic portion present in given reaction should be identified.

Concept Introduction:

Exergonic: The reaction is considered as exergonic if energy released since the reactants loses its energy, making the free energy is more negative hence making it spontaneous reaction.

Endergonic: The reaction is considered as endergonic if it needs more energy means that activation energy is much higher making the reaction non spontaneous.

Answer to Problem 21.20UKC

The exergonic portion is conversion of succinyl phosphate into succinate.

Explanation of Solution

Analyzing the given reaction it is clear that conversion of succinyl phosphate to succinate is exergonic since the phosphate bond in succinyl phosphate gets cleaved which releases energy.

Hence, exergonic portion is conversion of succinyl phosphate into succinate.

(b)

Interpretation Introduction

Interpretation:

The endergonic portion present in given reaction should be identified.

Concept Introduction:

Exergonic: The reaction is considered as exergonic if energy released since the reactants loses its energy making the free energy more negative hence making it spontaneous reaction.

Endergonic: The reaction is considered as endergonic if it needs more energy means that activation energy is much higher making the reaction non spontaneous.

Answer to Problem 21.20UKC

The endergonic portion is conversion of $ADP$ to $ATP$.

Explanation of Solution

Analyzing the given reaction it is clear that conversion of $ADP$ to $ATP$ is endergonic since the phosphate bond cleaved from succinyl phosphate gets attached to $ADP$.

Therefore, addition of phosphate group into $ADP$ requires energy.

Hence, endergonic portion is conversion of $ADP$ to $ATP$.