Biochemistry is the branch of science that explores the chemical processes and substances that occur within living organisms. Understanding the role of chemistry in biological systems is essential for comprehending the complexity of life at the molecular level. The interactions between molecules, cells, and organs are all governed by chemical reactions, making biochemistry a fundamental part of the study of biology and medicine.

One of the primary building blocks of life is the chemical bond. These bonds form the structure of macromolecules, such as proteins, nucleic acids, carbohydrates, and lipids, which perform vital functions in living systems. Proteins act as enzymes, catalyzing biochemical reactions, while nucleic acids store and transmit genetic information. Carbohydrates provide energy, and lipids contribute to cell membrane structures and energy reserves.

Water is another essential component of living systems. Its unique properties, such as polarity and the ability to form hydrogen bonds, allow it to act as a solvent for a variety of biochemical reactions.