A catalyzing science project
Key concepts Biology Biochemistry Enzymes Physiology Chemistry Introduction Background Enzymes have the ability to lower the activation energy of a chemical reaction by interacting with its reactants (the chemicals doing the reacting). Each enzyme has an active site, which is where the reaction takes place. These sites are like special pockets that are able to bind a chemical molecule. The compounds or molecules the enzyme reacts with are called their substrates. The enzyme pocket has a special shape so that only one specific substrate is able to bind to it, just like only one key fits into a specific lock. Once the molecule is bound to the enzyme, the chemical reaction takes place. Then, the reaction products are released from the pocket, and the enzyme is ready to start all over again with another substrate molecule. Catalase is a very common enzyme that is present in almost all organisms that are exposed to oxygen. The purpose of catalase in living cells is to protect them from oxidative damage, which can occur when cells or other molecules in the body come into contact with oxidative compounds. This damage is a natural result of reactions happening inside your cells. The reactions can include by-products such as hydrogen peroxide, which can be harmful to the body, just as how a by-product of a nice bonfire can be unwanted smoke that makes you cough or stings your eyes. To prevent such damage, the catalase enzyme helps getting rid of these compounds by breaking up hydrogen peroxide (H2O2) into harmless water and oxygen. Do you want to see the catalyze enzyme in action? In this activity you will disarm hydrogen peroxide with the help of catalase from yeast. Materials
Preparation
Procedure
Observations and results If there is no hydrogen peroxide present, the catalase cannot function, which is why in cup one you shouldn't have seen any bubble or foam production. Only when hydrogen peroxide is available, the catalase reaction can take place as you probably observed in the other cups. In fact, the catalase reaction is dependent on the substrate concentration. If you have an excess of enzyme but not enough substrate, the reaction will be limited by the substrate availability. Once you add more hydrogen peroxide to the solution, the reaction rate will increase as more substrate molecules can collide with the enzyme, forming more product. The result is an increasing amount of foam produced in your cup as you increase the amount of H2O2 in your reaction. You should have seen more foam being produced once you added another tablespoon of hydrogen peroxide to cup one, which should have resulted in a similar amount of foam as in cup two. However, at some point you will reach a substrate concentration at which the enzyme gets saturated and becomes the limiting factor. In this case you have to add more enzyme to speed up the reaction again. Many other factors affect the activity of enzymes as well. Most enzymes only function under optimal environmental conditions. If the pH or temperature deviates from these conditions too much, the enzyme reaction slows down significantly or does not work at all. You might have noticed that when doing the extra steps in the procedure. Cleanup More to explore This activity brought to you in partnership with Science Buddies Rights & Permissions Discover world-changing science. Explore our digital archive back to 1845, including articles by more than 150 Nobel Prize winners. Subscribe Now!Why is a change in reaction rate observed after 30 minutes?A change in the rate of reaction was seen after 30 mins because the rate of reaction levels off after 30 mins. It levels off because the substrate has been exhausted by the enzyme. This means that the enzyme has broken down most of the substrate so the change of enzyme and substrate encountering each other is low.
Which of the following statement best helps justify the inclusion of test tube 5 as a control in the experiment?Which of the following statements best helps justify the inclusion of test tube 5 in the experiment? It will act as a control for test tube 6 by showing the effect of the presence or absence of the enzyme. Researchers investigated the effect of urea on the three-dimensional structure of a certain enzyme.
Which of the following statements best predicts the effect that a change from a moderately acidic environment?Based on Figure 1, which of the following statements best predicts the effect that a change from a moderately acidic environment (pH near 6) to a basic environment will have on peroxidase activity? Peroxidase activity will decrease.
How do you determine the activity of an enzyme you can compare the concentration of enzyme before and after the reaction?To determine the activity of an enzyme, you can compare the concentration of the enzyme before and after the chemical reaction. False, because the enzyme is not used up in the reaction, the concentration of enzyme will not change. Which of the following factors can affect the rate of a chemical reaction?
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