Tears  On My Keyboard

Abstract

            The lac operon is a series of genes that controls the breaking down of the disaccharide lactose for energy. These series of three genes each have a specific part in this process. One gene is responsible for making the enzyme that brings lactose into the cell, another is responsible for producing the enzyme necessary to cleave lactose into a usable source once inside the cell, and the last produces and enzyme that disposes of the toxic byproducts produced from the cleaving of lactose. This operon is also controlled by three more gene elements that control when this operon is active and inactive. If there is no lactose present, the lac operon remains off. This operon is present in prokaryotes such as the bacteria E. coli. Even possessing this operon, E. coli would much rather use glucose as an energy source because it is much simpler, and requires less energy to utilize. The enzyme produced that cleaves lactose is β-galactosidase. It was hypothesized that β-galactosidase cleavage would occur the most in lactose only cultures, and the least in glucose only cultures because of the presence of glucose. An experiment was done to prove this, and the hypothesis was accepted. Data showed that much more activity was seen in the culture containing lactose only because lactose was indeed the only source of energy available; and least in cultures containing only glucose, and cultures containing glucose and lactose, because the bacteria would readily use glucose, even if lactose was available (Klug, Cummings, Spencer, & Palladino, 2009).