Final answer:
Cofactors and coenzymes are non-protein molecules that are necessary for enzyme function. They can be supplied by an organism's diet or produced by the organism itself. Vitamins are a common source of coenzymes.
Step-by-step explanation:
Many enzymes don't work optimally, or even at all, unless bound to other specific non-protein helper molecules. Two types of helper molecules are cofactors and coenzymes. Cofactors are inorganic ions such as iron (Fe++) and magnesium (Mg++). Coenzymes are organic helper molecules, with a basic atomic structure made up of carbon and hydrogen. Like enzymes, these molecules participate in reactions without being changed themselves and are ultimately recycled and reused. Vitamins are the source of coenzymes. Some vitamins are the precursors of coenzymes and others act directly as coenzymes. Vitamin C is a direct coenzyme for multiple enzymes that take part in building the important connective tissue, collagen. Therefore, enzyme function is, in part, regulated by the abundance of various cofactors and coenzymes, which may be supplied by an organism's diet or, in some cases, produced by the organism.