Dehydration Synthesis and Hydrolysis: Carbohydrates, proteins, and lipids are all synthesized and broken down by the same types of reactions. In dehydration synthesis, a hydrogen ion (H+) from one molecule joins with a hydroxyl group (OH-) from another molecule to form water (H2O), leaving the two molecules bonded to the same oxygen atom. For example, when two molecules of glucose are joined by dehydration synthesis, they form maltose and water (see below). In hydrolysis, complex organic molecules are broken down by the addition of the components of water – H+ and OH-. Both dehydration synthesis and hydrolysis require certain conditions of pH and temperature and the presence of particular enzymes. Briefly compare and contrast the dehydration synthesis and hydrolysis reactions.
The Correct Answer and Explanation is:
Correct Answer:
Dehydration synthesis builds complex molecules by removing water, while hydrolysis breaks down complex molecules by adding water. Dehydration synthesis forms bonds, whereas hydrolysis breaks bonds.
300-Word Explanation:
Dehydration synthesis and hydrolysis are chemical reactions essential in forming and breaking down macromolecules such as carbohydrates, proteins, and lipids. These reactions are opposite in nature but equally vital to cellular metabolism.
Dehydration synthesis, also known as a condensation reaction, occurs when two smaller molecules combine to form a larger molecule with the removal of a water molecule. During this process, a hydrogen ion (H⁺) from one molecule reacts with a hydroxyl group (OH⁻) from another, producing water (H₂O). This water is expelled, and a new covalent bond forms between the two molecules. For instance, when two glucose units are linked, a disaccharide such as maltose is formed alongside a water molecule. This type of reaction is critical in synthesizing polysaccharides, proteins, and triglycerides.
In contrast, hydrolysis is the process that breaks complex molecules into simpler ones through the addition of water. In hydrolysis, a water molecule splits into H⁺ and OH⁻, which then attach to the fragments of the original molecule, effectively reversing the dehydration synthesis. This reaction is used to digest macromolecules into their monomer components, such as converting proteins into amino acids or polysaccharides into monosaccharides.
Both reactions require specific enzymes to proceed efficiently, and they are influenced by temperature and pH conditions. Enzymes like maltase or protease facilitate hydrolysis, while synthase enzymes assist in dehydration synthesis.
In summary, dehydration synthesis constructs larger biological molecules by removing water, forming bonds, and requiring energy. Hydrolysis breaks these molecules apart by adding water, breaking bonds, and often releasing energy. Together, these reactions maintain the dynamic balance of molecular construction and decomposition in living organisms.
