* Carbohydrates: Monosaccharides (simple sugars) like glucose, fructose, and galactose. These can be joined together to form disaccharides (like sucrose) and polysaccharides (like starch and cellulose).

* Fats (Lipids): Fatty acids and glycerol. Glycerol is a three-carbon alcohol, and fatty acids are long chains of hydrocarbons with a carboxyl group at one end. These combine to form triglycerides, which are the most common type of fat.

* Proteins: Amino acids. There are 20 different amino acids, each with a unique side chain (R-group) that gives it specific properties. Amino acids are joined together by peptide bonds to form polypeptides, which fold into complex three-dimensional structures to form proteins.

* Nucleic Acids (DNA and RNA): Nucleotides. Nucleotides consist of three parts: a sugar (deoxyribose in DNA and ribose in RNA), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine (DNA only), and uracil (RNA only)). Nucleotides are linked together to form long chains called polynucleotides.