In biology, allolactose is an important isomer of lactose, a disaccharide made up of galactose and glucose. This molecule has special important in the study of genetics when the lac operon is being covered as an example of gene control. Small amounts of the molecule are produced when lactose enters an E. coli. Biology is the science of life (from the Greek words bios = life and logos = reasoned account). ... In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of bonds between atoms, but in which the atoms are arranged differently. ... Lactose is the sugar making up around 2-8% of the solids in milk. ... Chemistry A disaccharide is a sugar (a carbohydrate) composed of two monosaccharides. ... Galactose is a type of sugar found in milk products and sugar beets. ... A space-filling model of glucose Glucose, a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... The lac operon is a DNA sequence that governs the production of proteins, including two enzymes, for transporting and metabolizing lactose in the bacterium E. coli. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ...