Drosophila and the Cinnabar GeneDrosophila melanogaster, commonly known as the fruit fly, is used primarily as a model organism of human disease for genetic analysis. It was during the 20th century that D. melanogaster was considered the most significant model organism. D. melanogaster is small in size and short-lived with a good reproduction rate, perfect for breeding large numbers and generation counts for genetics experiments. Additionally, it has a small genome which makes it easier for geneticists to track changes at the molecular level. Geneticists have been able to discover many human genetic diseases through the homologous genome of human and fruit flies. It all started with a small group of people led by Thomas Hunt Morgan at Columbia University. Many principles and rules of genetic transmission that are still used in today's generation were established in Dr. Morgan's laboratory. Many animal models were used before fruit flies. By using the whole animal as a model it is possible to conduct limitations on the types and quantities of experiments. The use of Drosophila has succeeded in leading geneticists to overcome these limitations with enormous promise in the search for higher quality results. It was Frank Lutz, who wrote many articles on Drosophila, who introduced Dr. Morgan to Drosophila. Much experimental work on plants and animals was instead conducted on Drosophila. Through Drosophila the discovery of mutation, recombination, chromosome relocation and many other discoveries was made possible. The cinnabar gene, cn, codes for an enzyme essential in the formation of Drosophila eye color. It encodes the enzyme kynurenine-3-monooxygenase, which is essential in the biological pathway of the homochrome for the brown pi... in the center of the paper......ine, the mutation of cn1 or cn35k has occurred. When cinnabar mutations occur, the biological homochrome pathway is disrupted and the production of the brown pigment, xanthommatin, is inhibited, causing Drosophila to have bright red eyes. Phenotypic mutations characteristic of Drosophila are an essential aspect in studying and understanding recently discovered human genetic diseases. The mechanism by which enzymes metabolize tryptophan and intermediates of the biological homochrome pathway, the oxidation of kynuenine to 3-hydroxykynuenine, of the cinnabar gene have allowed geneticists to study the possibilities of neurotransmission factors in many brain diseases such as Alzheimer's and Parkinson's disease. The biological pathway of cinnabar mutations mimics a molecular evaluation of an approach that connects to the brain system of human biological processes.