Biochemistry

Biochemistry studies the chemistry of living systems: what their molecules are, how they recognize one another, and how their chemical reactions support the organization of a biological cell. It connects biology to chemical kinetics, stoichiometry and thermodynamics. A useful biochemical explanation follows both material and energy: which substrate becomes which reaction product, what sets the reaction rate, and how the transformation is driven.

Consider three connected examples. The stereochemistry of a sugar helps determine how it interacts with an enzyme's active site; the molecular formula alone cannot describe that recognition. Selective enzymes then direct material through metabolism, while ATP can participate in energy coupling that drives otherwise unfavourable transformations. These are different questions about the same working system, rather than three names for its energy supply.^[ref]

This viewpoint is useful because it separates possible explanations for a stopped process. Missing substrate, inactive enzyme, depleted ATP and accumulated reaction product call for different interventions. Studying a cell-free extract can isolate some of those causes while leaving a substantial chemical reaction network intact.

Biochemistry is the branch of science that explores the chemical processes and substances that occur within living organisms. It combines principles from both biology and chemistry to understand the molecular mechanisms of life. Biochemists study the structure, function, and interactions of biological molecules such as proteins, nucleic acids (DNA and RNA), carbohydrates, and lipids. Key areas of study within biochemistry include: 1. **Metabolism**: The biochemical pathways that convert nutrients into energy and the building blocks for cellular structures.