Final answer:
While most enzymes are proteins, there are also molecules such as cofactors, which are inorganic ions, and coenzymes, which are organic molecules that assist enzymes. The closest option to enzyme helpers would be nucleic acids known as ribozymes.
Step-by-step explanation:
Enzymes are specialized molecules that act as catalysts for biochemical reactions within living cells. While most enzymes are indeed proteins, there are other molecules that can function as enzymes or as enzyme helpers. These include cofactors, which are inorganic ions such as zinc or magnesium, necessary for the proper functioning of an enzyme. Another category is coenzymes, which are organic molecules that typically derive from vitamins and work together with enzymes to catalyze reactions.
The correct answer to the question "What other molecules (other than protein) can act as enzymes? What are they called?" is not directly listed among the options provided. However, the closest option in relation to enzyme helpers would be nucleic acids; coenzymes. Indeed, RNA molecules have been found to possess catalytic activity, and these RNA enzymes are known as ribozymes - a type of enzyme comprised of RNA rather than protein.