In what process do smaller molecules combine to form larger molecules?

The process in which smaller molecules combine to form larger molecules is known as anabolism. Anabolism encompasses a variety of metabolic pathways that build larger, more complex molecules from smaller units, which is essential for growth, repair, and maintenance of tissues in the body. For example, when amino acids link together to form proteins, or when simple sugars combine to create carbohydrates, these reactions are anabolic in nature.

This process often requires energy, usually derived from ATP, to drive the reactions that lead to the formation of new chemical bonds. Anabolism is a critical aspect of metabolism and is essential for the synthesis of cellular components, including macromolecules.

In contrast, the other terms refer to different processes. Decomposition involves the breakdown of complex molecules into simpler ones, which is the opposite of anabolism. Polymerization specifically refers to the process of combining small repeating units (monomers) into larger structures, such as proteins from amino acids or nucleotides forming nucleic acids, but it is a more specific term that falls under the broader category of anabolic processes. Catabolism focuses on the breakdown of larger molecules into smaller ones, releasing energy in the process.