A coenzyme is best described as which of the following?

A coenzyme is best described as which of the following?

• A. An inorganic molecule
• B. A metal ion
• C. An organic cofactor
• D. A protein cofactor

Answer: (C)

Coenzymes are organic cofactors that enable enzymes to carry out reactions by shuttling electrons, atoms, or groups between substrates. They are not proteins and are often derived from vitamins, with classic examples like NAD+ and FAD that transfer electrons and CoA that handles acetyl groups. Inorganic cofactors, such as metal ions like Mg2+ or Zn2+, serve a different role as non-organic helpers. Some coenzymes are tightly bound to the enzyme (prosthetic groups), while others bind and release during catalysis (cosubstrates). Because coenzymes are organic molecules that assist enzymatic function, the best description is an organic cofactor.

Coenzymes are organic cofactors that enable enzymes to carry out reactions by shuttling electrons, atoms, or groups between substrates. They are not proteins and are often derived from vitamins, with classic examples like NAD+ and FAD that transfer electrons and CoA that handles acetyl groups. Inorganic cofactors, such as metal ions like Mg2+ or Zn2+, serve a different role as non-organic helpers. Some coenzymes are tightly bound to the enzyme (prosthetic groups), while others bind and release during catalysis (cosubstrates). Because coenzymes are organic molecules that assist enzymatic function, the best description is an organic cofactor.