Coenzymes Quiz

A coenzyme is best described as:

• A structural protein that forms part of an enzyme's active site.

• A non-proteinaceous molecule that permanently binds to an enzyme.

• An organic molecule that transiently binds to an enzyme to facilitate a reaction, acting as a helper molecule.

• An inorganic ion that directly catalyses a biochemical reaction.

The term 'apoenzyme' refers specifically to:

• A fully functional enzyme with all necessary cofactors bound.

• An enzyme that is catalytically inactive due to the absence of its required coenzyme or cofactor.

• A coenzyme molecule that has been separated from its enzyme.

• An enzyme that is undergoing denaturation.

Coenzymes participate in enzyme catalysis by:

• Directly lowering the activation energy of a reaction.

• Acting as intermediate carriers of specific atoms or groups of atoms that are transferred during a reaction.

• Stabilising the enzyme-substrate complex through ionic bonds.

• Providing the necessary energy for the reaction to occur.

A holoenzyme is formed when:

• An enzyme is denatured by a change in pH or temperature.

• An apoenzyme binds with its specific coenzyme, thus becoming catalytically active.

• An enzyme undergoes phosphorylation, becoming deactivated.

• A substrate molecule binds to an enzyme.

Which of the following coenzymes is NOT primarily derived from a B vitamin?

• Thiamine pyrophosphate (TPP).

• Flavin mononucleotide (FMN).

• Adenosine triphosphate (ATP).

• Coenzyme A (CoA).

In the conversion of pyruvate to acetyl-CoA, which coenzyme plays a direct role in the decarboxylation step?

• FAD

• NAD+

• Thiamine pyrophosphate (TPP).

• Lipoic acid (LA)

The synthesis of Coenzyme A (CoA) in the body depends on the availability of:

• Vitamin B1 (Thiamine).

• Vitamin B2 (Riboflavin).

• Vitamin B5 (Pantothenic acid).

• Vitamin B3 (Niacin)

The primary function of FMN in biological systems is to:

• Directly reduce oxygen to water.

• Participate as a cofactor in oxidation-reduction reactions, particularly those catalysed by oxidoreductases.

• Serve as an energy carrier.

• Act as an inhibitor in metabolic pathways.

Which of the following biochemical pathways is NOT directly associated with FMN?

• Riboflavin metabolism

• Pyrimidine metabolism

• Fatty acid synthesis.

• Pantothenate and CoA biosynthesis

In the food industry, FMN is primarily used as:

• A pH regulator.

• A food colouring agent, imparting an orange-red hue.

• An emulsifier.

• A flavour enhancer.