Anabolic reactions are metabolic processes that build larger molecules from smaller ones. These reactions require energy, which is often derived from the breakdown of ATP (adenosine triphosphate). Anabolic processes are essential for growth, repair, and maintenance of tissues in living organisms. Examples of anabolic reactions include the synthesis of proteins from amino acids and the formation of glycogen from glucose. These reactions play a crucial role in the body's ability to store energy and create complex structures necessary for life.