[Sophomore Biology: Organic Molecules Menu]


Dehydration reactions involve monomer molecules (like amino acids or simple sugars) bonding to each other. When they bond, an OH and an H (H2O) are removed from them. Because the newly bonded molecule loses water, this is known as dehydration. The upper diagram illustrates dehydration, where the green-shaded circles represent individual monomers.

Hydrolysis reactions involve breaking polymer molecules such as polypeptides (large proteins) or starches into their monomer forms (amino acids and glucose molecules respectively). This can only be done when water is added to each of the bonds between the monmer molecules (shown as green shaded circles below). The second diagram below illustrates the process of hydrolysis, where water is added to break the big molecule into smaller components.

Dehydration Reactions (Building of larger molecules) add energy to organic molecules.

Hydrolysis Reactions (those that tear apart molecules) release energy from the molecules.

An example of a dehydration reaction.