A molecular model of vitamin B7 (biotin), a coenzyme necessary for cell growth, the production of fatty acids, and the metabolism of fats and amino acids. Intestinal bacteria produce most of the body's daily requirement of biotin, but it can also be found in leafy green vegetables, liver, and raw egg yolk. Atoms are colored light gray (hydrogen), dark gray (carbon), blue (nitrogen), red (oxygen), and yellow (sulfer).