What process combines two molecules by removing a water molecule?

The process that combines two molecules by removing a water molecule is known as dehydration synthesis. This reaction is critical in the formation of larger molecules from simpler ones. During dehydration synthesis, a hydroxyl group (-OH) is removed from one molecule and a hydrogen atom (H) is taken from another, resulting in the release of a water molecule (H2O). The remaining parts of these two molecules then bond together, forming a larger compound.

This mechanism is fundamental in building polymers, such as proteins from amino acids or carbohydrates from monosaccharides. It plays a key role in various biological processes, including the synthesis of DNA and RNA, where nucleotides are linked together.

Hydrolysis, on the other hand, is the process of breaking down molecules by adding water, which is the opposite of dehydration synthesis. Condensation can refer to the formation of a liquid from a vapor, but in a biological context, it can also describe reactions that result in the formation of bonds, typically involving the loss of water, similar to dehydration synthesis. Combustion refers to a chemical reaction involving the rapid combination of a substance with oxygen, resulting in release of energy and is not related to the formation of larger biological molecules.