PEP Carboxykinase

The video tutorial explains the reversal of pyruvate kinase, a highly exergonic reaction in glycolysis, requiring two enzymes: pyruvate carboxylase and phosphoenolpyruvate carboxykinase. The mechanism of phosphoenolpyruvate carboxykinase is detailed, highlighting its GTP dependency and the role of entropy in driving the reaction. The tutorial analyzes the reactants and products, emphasizing the positive delta S and its impact on Gibbs free energy, making the reaction feasible. The video concludes with a recap and notes on the enzyme's dual mitochondrial and cytosolic presence.

Why can't pyruvate kinase be reversed using the same enzyme?

• It is an endergonic reaction.

• It is a highly exergonic reaction.

• It requires ATP.

• It is not involved in glycolysis.

What molecule does phosphoenolpyruvate carboxykinase use instead of ATP?

• UTP

• GTP

• CTP

• TTP

What is the role of entropy in the reaction catalyzed by phosphoenolpyruvate carboxykinase?

• It stabilizes the reactants.

• It drives the reaction forward.

• It increases the reaction's free energy.

• It decreases the reaction rate.

What is the first product released during the reaction mechanism of phosphoenolpyruvate carboxykinase?

• GTP

• GDP

• Carbon dioxide

• Phosphoenolpyruvate

Which of the following is a characteristic of phosphoenolpyruvate?

• It is a low-energy molecule.

• It is a derivative of a ketone.

• It is highly unstable and high-energy.

• It is a stable molecule.

How many products are formed in the reaction catalyzed by phosphoenolpyruvate carboxykinase?

• Four

• Three

• Two

• One

Where is phosphoenolpyruvate carboxykinase located within the cell?

• In the nucleus

• In both the mitochondria and cytosol

• Only in the mitochondria

• Only in the cytosol