Metabolism & Glycolysis – Lecture Review

25 flashcards reviewing key enzymes, reactions, and thermodynamic principles from the glycolysis and metabolism lecture.

Write one irreversible glycolytic reaction.

Fructose-6-phosphate + ATP → Fructose-1,6-bisphosphate + ADP (catalyzed by phosphofructokinase-1).

Metabolism is the totality of an organism’s chemical reactions.

True.

What characterizes a metabolic pathway in terms of molecules and catalysis?

It starts with a specific molecule, ends with a product, and each step is catalyzed by a specific enzyme.

Kinetic energy is energy associated with location or structure.

False (that is potential energy; kinetic energy is associated with motion).

According to the second law of thermodynamics, does every energy transfer decrease the entropy of the universe?

False; energy transfers increase the entropy of the universe.

Define a living system’s free energy.

Energy that can do work when temperature and pressure are uniform throughout the system.

Are only processes with a positive ΔG spontaneous?

False; spontaneous processes have a negative ΔG.

Give the full reaction catalyzed by triose phosphate isomerase.

Dihydroxyacetone phosphate ⇌ Glyceraldehyde-3-phosphate.

Phosphoenolpyruvate contains a low-energy phosphate bond.

False; it contains a high-energy phosphate bond.

Which enzyme converts 3-phosphoglycerate to 2-phosphoglycerate?

Phosphoglycerate mutase.

Define catabolism.

The breakdown of complex molecules into simpler ones, releasing energy.

Pyruvate dehydrogenase is one of the enzymes of the pyruvate dehydrogenase complex.

True.

What metabolic role does the pyruvate dehydrogenase complex play?

It links glycolysis to the tricarboxylic acid (TCA) cycle.

Fructose-1,6-bisphosphate contains a high-energy phosphate bond.

False.

Which enzyme converts dihydroxyacetone phosphate (DHAP) to glyceraldehyde-3-phosphate (G3P)?

Triose phosphate isomerase.

What conversion does phosphoglycerate mutase catalyze in glycolysis?

3-Phosphoglycerate → 2-Phosphoglycerate.

Which step of glycolysis produces NADH?

Glyceraldehyde-3-phosphate → 1,3-bisphosphoglycerate (catalyzed by glyceraldehyde-3-phosphate dehydrogenase).

Which statement about the pyruvate dehydrogenase complex is correct?

It requires NAD⁺ as a cofactor.

Hexokinase is an allosteric enzyme and can be inhibited by citrate.

False.

Define glycolysis.

The metabolic pathway that converts glucose to pyruvate in the cytosol, producing ATP and NADH.

Write the reaction catalyzed by phosphoglucose isomerase.

Glucose-6-phosphate ⇌ Fructose-6-phosphate.

Is the reaction catalyzed by phosphofructokinase spontaneous?

Yes; it proceeds with a large negative ΔG under cellular conditions.

In terms of free energy, what is characteristic of equilibrium?

Equilibrium represents a state of maximum stability (minimum free energy).

Give the full reaction for the conversion of 2-phosphoglycerate to phosphoenolpyruvate.

2-Phosphoglycerate → Phosphoenolpyruvate + H₂O (catalyzed by enolase).

During a spontaneous process, how do free energy and stability change?

Free energy decreases and stability increases.