Summary BIOLOGY Enzyme lab: Practice IA Catalase + concentration

Background An enzyme is a protein molecule that acts as a catalyst to increase the rate of a reaction. A catalyst is a chemical that speeds up a chemical reaction but is not used up in the reaction. Enzymes work by fitting with a specific substrate ( reactant molecule ). When the substrate binds to the active site it’s bonds become less stable and therefore are more likely to be altered and form new bonds. Many factors can affect the rate of enzyme action such as the temperature, the pH and the enzyme or substrate concentration. If the temperature is too low then the bonds are not flexible enough to enable substrate molecules to fit properly. If the temperature is too high then the bonds are too weak to maintain the enzyme's shape. If the concentration of enzyme is increased then the reactions will occur faster. The pH can also affect the rate of reaction. The topic I chose allows me to understand how the concentration of enzyme affects the rate of reaction of an enzyme. In our body cells use enzymes to break down poisonous chemicals into harmless substances such as breaking down hydrogen peroxide, a toxic chemical, into 2 harmless substances; water and oxygen, which is done by the enzyme I have chosen to study; Catalase. Without catalase, the hydrogen peroxide that the body produces during the metabolic process would build up to toxic levels. Catalase can be found in many places such as the liver, potatoes, wheat sprouts, and carrots. It is important to supplement your body with a good amount of catalase to keep your body free of this specific toxin. The formula for the breaking down of hydrogen peroxide is what follows: 2 H2O2 → 2 H2O + O2 Problem How does the concentration of the enzyme catalase affect the rate of enzyme activity in potatoes? Hypothesis If more catalase (the enzyme) is provided to hydrogen peroxide then the rate at which gas is produced will increase and change because there is more enzyme present to bind with the substrate and therefore change and form new bonds. Eventually the enzyme concentration becomes saturated and then the reaction rate will decrease and create less gas. Experimental design In order to test the effect of enzyme concentration on the rate of reaction of enzyme activity multiple trials were done of each concentration. For each test, a tub of water with a 100mL graduated cylinder held upside down filled to the top with water with a clamp was used. A cylinder was placed right below the edge of the water to keep all of the water inside and to allow space for the test tube to go underneath. This cylinder served as a method to measure the amount of gas produced per 12 seconds. 5 trials were done for each manipulation of enzyme concentration by changing the number of potatoes added to the substrate which is hydrogen peroxide. 10 mL of hydrogen peroxide was provided for each trial done. The 12 seconds were recorded with a stopwatch. Each potato added weighed the same around 2.5g. Variables: - Independent variable: The (concentration) number of square potato slices. - Dependent variable: Amount of gas produced (mL) - Controlled variable: Temperature of potatoes; to be kept in room temperature. Volume of hydrogen peroxide (10mL). Mass of each square of potato (2.5g). The time the test tube is under the graduated cylinder (12 seconds). Materials - Two medium test tubes - One-holed rubber stopper to seal the test tube - One 100 mL graduated cylinder - One retort stand - One test tube clamp to hold cylinder - One deep tub to hold water - One stopwatch ( ± 0.01seconds) - One bottle of hydrogen peroxide (250 mL for 25 times) - Two potatoes as the source of catalase (around 2.5g for each square cube around same size) - One 10 mL pipette - One rubber pipette bulb - One 10 mL beaker to hold hydrogen peroxide - One two decimal laboratory scale - One scalpel - One container with water to hold potato pieces - Distilled water