Six elements make up more than 99 percent of the mass of your cells
Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur account for over 99 percent of cell mass. Biochemistry studies how those few ingredients become living machinery, a field that arguably began when a chemist made urea in a flask in 1828 and challenged the old belief that only life could make life's molecules.
For centuries many thinkers assumed living matter contained a special vital principle, so that only organisms could produce organic molecules. In 1828 Friedrich Wöhler synthesised urea from potassium cyanate and ammonium sulfate, largely by accident. Some treat this as the moment vitalism died and organic chemistry was born, though others dispute that it settled the matter so neatly. Candidates for the birth of biochemistry itself vary: Anselme Payen's discovery of the first enzyme, diastase, in 1833; Justus von Liebig's 1842 book on animal chemistry; or Eduard Buchner's 1897 demonstration that fermentation can happen in cell-free extracts.
The word appeared in print in 1858, in Vinzenz Kletzinsky's compendium published in Vienna. Felix Hoppe-Seyler used it in 1877 as a synonym for physiological chemistry, though Carl Neuberg is often credited with coining it in 1903. Since the mid-20th century, techniques such as chromatography, X-ray diffraction, NMR spectroscopy and electron microscopy have opened up molecules and metabolic pathways in detail. In the 1950s Watson, Crick, Rosalind Franklin and Maurice Wilkins worked out the structure of DNA, and in 1958 George Beadle and Edward Tatum shared a Nobel Prize for showing, in fungi, that one gene yields one enzyme.
Life runs on roughly two dozen elements. Most rare elements are unnecessary, with selenium and iodine as exceptions, while some common ones such as aluminium and titanium go unused. Needs differ: all animals require sodium but only a few plants do, and plants need boron and silicon that animals may not. Beyond the six bulk elements, humans need substantial magnesium, potassium, sodium and calcium plus traces of possibly 18 more.
The molecules built from them fall into four big classes: carbohydrates, lipids, proteins and nucleic acids. Many are polymers, chains of repeating units linked by reactions that release water. Carbohydrates are the most abundant biomolecules on Earth. Sucrose joins glucose to fructose, lactose joins glucose to galactose, and plants store energy as starch while animals use glycogen. The field's findings feed medicine, nutrition and agriculture, and combined with engineering they underpin biotechnology.
Source: Biochemistry
