Condensation reactions are characterized by the joining of two molecules to make a more complex molecule and it is made with the loss of water or condensation. One of the two molecules involved in this reaction is always ammonia or water. Condensation reactions are used to make pharmaceuticals, such as amino acids, which are essential to your body for its functions.

In biology, condensation reactions are used in the manufacturing of biological macromolecules to create carbohydrates, lipids, nucleic acids and proteins from the simpler molecules of their sub units. These are all needed by your body for good nutrition and for bodily functions. In condensation reactions, when the two or more molecules are joined, they actually get smaller because they lose water. Therefore, the end product is smaller than the total of each individual molecule added together.

A dehydration reaction is also referred to as hydrolysis. Dehydration reactions involve a large molecule being split into smaller areas by the breaking of a bond. In doing so, it adds H^- to one area and OH^- to the other. It requires the addition of water to make simpler substances. Hydrolysis means splitting by water. An example of dehydration reactions is when you digest your food and break it down into smaller particles. A condensation reaction can also be called a dehydration action if it produces acid anhydrades plus water.

Amino acids are the building blocks of proteins in your body. Proteins make up approximately 15 percent of your body mass. You have nine essential amino acids that are obtained from food; 11 are non-essential, though, and are made in a lab by using the condensation reaction to achieve them. When amino acids dissolve in water, they ionize. A proton transfers for the carboxylic group to the amine group to form an amino acid for consumption.

In organic chemistry, an aldol condensation is a condensation reaction in which an enol or enolate ion reacts with a carbonyl compound making a β-hydroxyaldehyde or β-hydroxyketone, which is followed by dehydration and ending in a conjugated enone. Aldol is the combination of an aldehyde and alcohol, which naturally occurs in many molecules and is manufactured as pharmaceuticals, such as amino acids. Aldol condensations are important for organic synthesis as they provide a good formation of carbon-to-carbon bonds.