Biochemistry is the study of chemical reactions and molecules within living organisms. It involves studying biomolecules like amino acids, monosaccharides, and nucleotides that are composed of elements like carbon, hydrogen, oxygen, and nitrogen. There are over 10,000 biomolecules in the human body. Biochemistry helps with drug formulation, improvement, determining half-life and storage conditions, and estimating expiry dates. The cell is the basic structural and functional unit of living things, and cells contain biomolecules that serve as building blocks. Major biomolecules include proteins, DNA, RNA, carbohydrates, and lipids.