Biochemical reactions are processes that occur within living organisms, involving the transformation of molecules through chemical changes. These reactions are essential for maintaining life, as they enable functions such as metabolism, energy production, and cellular repair. Enzymes, which are specialized proteins, often facilitate these reactions by lowering the energy required for them to occur. These reactions can be categorized into two main types: catabolic reactions, which break down larger molecules into smaller ones to release energy, and anabolic reactions, which build larger molecules from smaller units, requiring energy input. Together, these processes support growth, reproduction, and overall cellular function.