Forming Biological Compounds

Condensation and Hydrolysis Reactions

Condensation reactions are processes that result in the formation of large molecules, linked via covalent bonds, with a molecule of water produced.
In hydrolysis reactions, large molecules are broken down into their constituent parts through the addition of water.

Monomers are small, basic molecular units that are capable of binding to other monomers to form more complex structures. Monosaccharides, amino acids, and nucleotides are monomers.
Polymers are large, complex biomolecules assembled from monomers. Examples include polysaccharides, proteins, and nucleic acids.

Carbohydrates are comprised of carbon, hydrogen and oxygen. They serve as energy stores, structural components, and recognition molecules.
Monosaccharides are the simplest carbohydrates and serve as monomers for larger carbohydrates. Glucose is a common example.
Disaccharides are formed from two monosaccharides and are involved in energy storage and transport. Sucrose is a common example.
Polysaccharides, formed from multiple monosaccharides, serve key roles ranging from energy storage (like starch) to structural support (like cellulose).

Proteins are composed of amino acids connected through peptide bonds.
A peptide bond is a covalent bond formed between the amino group of one amino acid and the carboxylic group of another, producing water in a condensation reaction.
Proteins have four levels of structure: primary, secondary, tertiary, and quaternary. Each level contributes to a protein’s unique shape and function.

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are polymers of nucleotides.
Nucleotides consist of a phosphate group, a sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base.
DNA carries the genetic information for a cell, and RNA has a variety of roles relating to protein synthesis and regulation.

Lipids are a group of hydrophobic (water-repelling) molecules, not based on repeating monomer units.
Triglycerides are lipids used for energy storage, while phospholipids form key structural components of cell membranes.
Steroids, another form of lipid, are involved in many hormonal and structural roles.