Biochemistry is particularly interested in the structures, functions and interactions of biological macromolecules such as carbohydrates, lipids, proteins and nucleic acids, which constitute cellular structures and carry out many biological functions. Cellular chemistry also depends on smaller molecules and ions. The latter can be inorganic, for example the hydronium ion H3O+, the hydroxyl OH− or metal cations, or organic, such as the amino acids which constitute proteins.
These chemical species are essentially made up of hydrogen, carbon, oxygen and nitrogen; lipids and nucleic acids additionally contain phosphorus, while proteins contain sulfur and ions and some cofactors consist of or include trace elements such as iron, cobalt, copper, zinc, molybdenum, l iodine, bromine and selenium.
The results of biochemistry find applications in many fields such as medicine, dietetics and agriculture; in medicine, biochemists study the causes of diseases and treatments likely to cure them; nutritionists use the results of biochemistry to design healthy diets while understanding biochemical mechanisms allows us to understand the effects of dietary deficiencies; applied to agronomy, biochemistry makes it possible to design fertilizers adapted to different types of crops and soils as well as to optimize crop yield, crop storage and the elimination of parasites.