Final answer:
Enzymes are primarily proteins that function as biological catalysts in living organisms, speeding up chemical reactions by lowering activation energy. They are specific due to their unique structures, with an active site that interacts with substrates to facilitate reactions.
Step-by-step explanation:
The type of macromolecule that most enzymes are is proteins. Enzymes are biological catalysts that accelerate chemical reactions in living organisms by lowering activation energy barriers. An enzyme's specificity for its reaction is due to its unique structure, which is a result of the arrangement and interactions of its amino acid components. At the center of an enzyme's catalytic activity is the active site, where substrate binding occurs. This interaction often follows the induced fit model, changing the enzyme's shape to better facilitate the reaction. Once the reaction is complete, the enzyme releases the products and returns to its original shape, ready to catalyze another reaction.
Proteins are one out of four major types of macromolecules found in living organisms; the others include carbohydrates, lipids, and nucleic acids. Enzyme-catalyzed reactions are critical to various biological processes, such as digestion, where different enzymes like amylase, lactase, and lipases break down respective macromolecules to provide energy for cells.