What type of reactions use energy to build complex molecules?

Anabolic reactions are those biochemical processes that require energy to synthesize complex molecules from simpler ones. This type of reaction is fundamental to growth and repair in living organisms, as it involves the construction of macromolecules such as proteins, nucleic acids, and polysaccharides. Anabolic reactions utilize energy, often derived from ATP (adenosine triphosphate), to drive the formation of these essential compounds necessary for cellular functions.

In contrast, catabolic reactions break down complex molecules into simpler ones, releasing energy in the process. Metabolic reactions encompass both anabolism and catabolism, making it a broader term that includes various biochemical processes, but it does not specifically highlight the energy-consuming aspect of building molecules. Decomposition reactions generally refer to the breakdown of compounds into simpler substances, further emphasizing the distinction between the energy-utilizing nature of anabolic reactions and those that release energy. Thus, anabolic reactions specifically denote the processes that build complex molecules and require energy input.