1) Which of the following compounds is NOT an enzyme?A) dehydrogenaseB) cellulaseC) coenzyme AD) β-galactosidaseE) sucrase
The Correct Answer and Explanation is :
The correct answer is C) coenzyme A.
Explanation:
Enzymes are biological catalysts that speed up the rate of chemical reactions in living organisms. They are typically proteins (or sometimes RNA molecules, in the case of ribozymes) that facilitate the conversion of substrates into products. Enzymes work by lowering the activation energy of reactions and are highly specific to the reactions they catalyze. Let’s review each option to understand why coenzyme A is not an enzyme:
- A) Dehydrogenase: This is an enzyme that catalyzes the removal of hydrogen atoms from a substrate, often involved in redox reactions. Examples include lactate dehydrogenase and alcohol dehydrogenase. These enzymes play crucial roles in metabolic pathways like glycolysis and the citric acid cycle.
- B) Cellulase: This is an enzyme that breaks down cellulose into glucose or smaller carbohydrate units. It is commonly found in microorganisms that digest plant matter, as well as in certain animals like termites. Cellulase aids in the breakdown of plant cell walls.
- C) Coenzyme A: Coenzyme A (often abbreviated as CoA) is not an enzyme. Instead, it is a cofactor or coenzyme that assists enzymes in their catalytic functions. Coenzyme A is a small molecule that plays a critical role in the metabolism of fatty acids and carbohydrates. It is involved in reactions like the formation of acetyl-CoA, which is important in the citric acid cycle, but it does not catalyze reactions on its own.
- D) β-Galactosidase: This is an enzyme that breaks down lactose (a disaccharide) into its monosaccharide components, glucose and galactose. It is important for organisms that digest lactose, such as in the small intestine of humans.
- E) Sucrase: Sucrase is an enzyme that catalyzes the hydrolysis of sucrose (table sugar) into glucose and fructose. It plays a crucial role in the digestion of sucrose in humans and many other organisms.
Thus, coenzyme A is the only compound listed that is not an enzyme. It is a helper molecule, not a catalyst itself.