Final answer:
Enzymes are protein-based biological catalysts that accelerate chemical reactions in living organisms by lowering the activation energy, and they have a special active site for binding substrates.
Step-by-step explanation:
Enzymes are biological catalysts primarily composed of proteins, although some can be made from nucleic acids. They accelerate chemical reactions in living organisms by lowering the activation energy, thereby allowing processes necessary for life to occur more quickly and efficiently. A defining characteristic of enzymes is their use of an active site to bind substrates—the molecules they act on—to form precise enzyme-substrate complexes. This alignment often makes the reaction more likely to occur by correctly positioning the substrate for the reaction.
The specific nature of this binding is crucial; the induced fit model describes how the active site can adapt its shape upon substrate attachment to optimize the interaction, unlike the older lock and key model which depicted a static active site. Enzymes are vital for various functions and industrial applications, such as the food and dairy industry, biofuel production, and the paper industry.