What prevents the first reactions of glycolysis from running in reverse, thereby building and metabolizing glucose at the same time?
A)Free radicals are produced by glycolysis reactions that run in reverse; therefore, cells use antioxidants to inhibit these reactions.
B)The electron transfer phosphorylation required to generate ATP during glycolysis cannot run in reverse, because the coenzymes they require are only found in the mitochondria.
C)The glycolysis reactions are unable to run in reverse; instead, excess energy is stored as fat, not carbohydrates.
D)During times of excess blood glucose, the hormone insulin is required to stimulate the reverse reaction to produce glycogen.
E)Due to the energy input required for glycolysis to proceed, the reverse reaction would require too much energy to run spontaneously.

Question

Quizplus · Accepted Answer

The first reactions of glycolysis require an input of energy to proceed, meaning that the reverse reaction, which would release energy, would require an input of energy to occur. This makes the reverse reaction energetically unfavorable and prevents it from occurring spontaneously. Additionally, building glucose from smaller molecules requires different enzymes and reactions than breaking down glucose during glycolysis, so the pathways are inherently separate.

What Prevents the First Reactions of Glycolysis from Running in Reverse