Final answer:
Structures made of proteins that act as catalysts to metabolic reactions are known as protein enzymes, a category that excludes ribozymes as they are RNA-based, not protein-based. Hence, the correct option in the final answer that includes structures made up of proteins acting as catalysts is Protein enzymes (Option B).
Step-by-step explanation:
Enzymes are biological molecules that function as catalysts in metabolic reactions, thus playing a crucial role in facilitating life's biochemical processes. These enzymes are predominantly proteins made from chains of amino acids that fold into intricate three-dimensional shapes, enabling them to precisely bind to specific substrate molecules.
Enzymes accelerate chemical reactions by lowering their activation energy, thereby allowing reactions to proceed rapidly and more efficiently, which is essential for maintaining the vital functions within living organisms. These enzymes are highly specific, leading to the fact that they are tailored to catalyze only specific reactions or types of reactions, whether those are anabolic, catabolic, or simple transformation processes.
It’s noteworthy that enzymes are not consumed during the reactions they catalyze, meaning they can be used repeatedly.
Ribozymes, on the other hand, are not composed of proteins but rather RNA molecules that also have catalytic properties. Therefore, when answering the question, "Which structures are made up of proteins that act as catalysts to metabolic reactions?" the mention of ribozymes can be misleading as they are not protein-based. Hence, the correct option in the final answer that includes structures made up of proteins acting as catalysts is Protein enzymes (Option B).