Which of the following best describes enzymes?

Enzymes are best described as proteins that facilitate biochemical reactions because they serve as catalysts in various chemical processes within living organisms. By lowering the activation energy required for a reaction to occur, enzymes make it easier and faster for reactions to take place, ultimately aiding in vital biological functions such as metabolism and DNA replication.

Being proteins means that enzymes are made up of long chains of amino acids, which fold into specific three-dimensional shapes crucial for their activity. This specific shape allows them to bind to substrates—the molecules upon which they act—at their active sites, resulting in the conversion of substrates into products.

The other options describe concepts that are either inaccurate or not related to enzymes. Enzymes are not consumed in reactions; they can be reused multiple times to catalyze reactions. They also are not carbohydrates; carbohydrates are primarily involved in energy storage and supply, rather than acting as biological catalysts. Furthermore, nucleic acids, such as DNA and RNA, are essential for genetic information transmission, but they do not function as enzymes in biochemical reactions. Thus, the characterization of enzymes as proteins that facilitate biochemical reactions is the most accurate and comprehensive description.