Beta Galactosidase Lab Report

Enzymes are proteins that significantly speed up the rate of chemical reactions that take place within cells. Some enzymes help to break large molecules into smaller pieces that are more easily absorbed by the body. Other enzymes help bind two molecules together to produce a new molecule. Enzymes are selective catalysts, meaning that each enzyme only speeds up a specific reaction. The molecules that an enzyme works with are called substrates. The substrates bind to a region on the enzyme called the active site. The active site is precisely shaped to hold specific substrates. Beta-galactosidase is one of the three genes in the lac operon. A lac operon is an operon required for the digestion of lactose in bacteria cells. B-galactosidase converts lactose, a disaccharide, into glucose and galactose, monosaccharides. The substrate for beta-galalactoside is ortho-nitrophenyl-B-galactoside. ONPG is structured similarly to lactose. The purpose of the experiment was to add a competitive inhibitor to observe if the reaction rate would slow down. A competitive inhibitor is when the inhibitor binds to the active site on the enzyme and prevents the binds of the substrate

The competitive inhibitor that was added was lactose. We predicted this because competitive inhibitors block and bind to the active site so it will slow down the binding of the desired substrate. An alternative hypothesis that came up was that the reaction of substrate would stay consistent as if no inhibitor was added. The enzyme could reject the inhibitor if it does not fit in the active site, causing the substrate to bind as it normally would. Our results showed that with the addition of lactose, the reaction did slow down a considerably