Cofactors are required for the catalytic function of which biological molecules?

Cofactors are essential for the catalytic function of enzymes, which are biological molecules that accelerate chemical reactions in living organisms. Enzymes often require additional non-protein molecules, known as cofactors, to facilitate their catalytic activities. These cofactors can be metal ions or organic molecules, and they help in stabilizing the enzyme's structure, assisting in the transformation of substrates into products, or participating directly in the reaction process.

Although substrates, products, and coenzymes are related to enzyme function, they play different roles. Substrates are the molecules upon which enzymes act, while products are the resulting molecules after a reaction has occurred. Coenzymes, on the other hand, are a specific type of cofactor that are organic molecules and often derived from vitamins; while these are indeed important for some enzymes, they are not the only type of cofactor. The defining characteristic of the correct answer is that enzymes themselves require cofactors for their active functioning, making them central to the process of catalysis in biochemical reactions.