Carbohydrates consist of carbon, hydrogen, and oxygen atoms. They are classified into monosaccharides (simple sugars like glucose), disaccharides (two monosaccharides like sucrose), and polysaccharides (complex carbohydrates like starch and cellulose). They serve as a primary energy source, storage of energy, and structural components in cells.

Proteins are made up of amino acids and play a vital role in the body. They function as enzymes (catalysts for biochemical reactions), provide structural support (e.g., collagen in connective tissues), transport molecules (e.g., hemoglobin), and are involved in immune responses (e.g., antibodies).

Nucleic acids, such as DNA and RNA, are composed of nucleotides. DNA stores genetic information, which is passed from one generation to the next, while RNA helps in protein synthesis by translating the genetic code into functional proteins.