The body has 4 general classes of molecules: carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates are simply sugars. The smallest type of sugar, like glucose, is called monosaccharides. Disaccharides are 2 monosaccharides combined. An example is when glucose and fructose is joined together to form sucrose, a disaccharide. A polysaccharide is a chain of monosaccharides. Polysaccharides act as a fuel source. Whenever you fast, the polysaccharide, glycogen, is broken down into the monosaccharide, glucose, for your body to use.

The next type of organic molecule is called lipids, or fats. Fatty acids are used by the body as energy. Triglycerides have three fatty acids inside, hence the “tri,” and are used for energy storage. Phospholipids are extremely important, since they form the membranes of all cells of the body. Next are steroids, which consist of cholesterol, cortisol, estrogen, and testosterone.

The building blocks of proteins are called amino acids. When amino acids are linked together, it becomes a polypeptide. Proteins have many functions in the body and can act as antibodies, enzymes, messengers, and transporters. Antibodies protect the body from foreign particles. Enzymes catalyze or make reactions in the body occur faster. Messenger proteins, like hormones, send signals between different cells. Transporter proteins are like taxis that bind to atoms or molecules and then bring them to their destination. Lastly, proteins give the body structural support and shape.

Nucleic acids include DNA and RNA. DNA, deoxyribose nucleic acid, is a complex recipe for how a person should be created. RNA, ribonucleic acid, decodes the genetic information into instructions for how the amino acids should be linked together to form polypeptides. Both DNA and RNA are made of nucleotides and each nucleotide is made of a phosphate, sugar, and base.