You will probably see a numerous numbers of tiny flies flying around on your produce. These little creatures are probably fruit flies. Fruit flies can be a problem year round, but are especially common during late summer or fall because they are attracted to ripened or fermenting fruits and vegetables. These fruit flies are also known as drosophila. These little flies, only about 4 millimeters in length, are named drosophila because they live and feed on the fungi growing on spoiled fruits and vegetables.
Different segments develop different organs and internal structures.
During development a cell decides what role it will play. It then produces the appropriate molecules and acts as transcription factors to activate other genes to complete role in the developmental process. For example, a cell can be determined to divide more to become part of an eye, an antenna, a leg, or part of the wing. Early in development gene products RNA and proteins are produced which act as transcription factors of different parts of the embryo. These products turn other genes on and off, which regulate what gene products are made in a specific part of the embryo.