Purpose: Cells produce toxic wastes, in this experiment hydrogen peroxide, and without some sort of molecule to break it down the cell will die, along with the organism itself. However with the aid of an enzyme, catalase, hydrogen peroxide is able to be broken down into an intermediate and thereafter harmless substances water and oxygen. The goal of this lab is to measure the reaction rate of this process in different substances such as a liver, a vegetable, and breast tissue. By using variables such a pH and temperature we are able to how the rate of reaction is altered or improved. If it has improved, the optimum has been discovered and the enzyme will create a higher reaction rate. If above the optimal points, proteins will denature and the reaction rate will remain the same. This is vital for cellular activity for if homeostasis is not reached enzymatic activity will decrease or the enzymes will simply denature and the toxicity within the cell will increase killing the cell. Enzyme Lab
1 molar HCl solution
1 molar NaOh Solutions
6 test tubes
10-ml Graduated cylinder
40 ml 3% Hydrogen peroxide solutions
Straight-edge razor blade
Scissors and Forceps
pH Paper (optional)
Test Tube Holders
Ice Bath Warm Water Bath
Boiling Water Bath
1. Place 2 ml of the 3% hydrogen peroxide solution into a clean test tube 2. Using forceps and scissors cut a small piece of liver and add it to the test tube. Push it into the hydrogen peroxide with a stirring rod. Observe the bubbles.
What gas is being released? Oxygen
Throughout this investigation you will estimate the rate of reaction (how rapidly the solution bubbles) on a scale of 0-5 (0= no reaction, 1=slow… 5= very fast). Assume that the reaction in step 2 proceeded at a rate of “4.”
Recall that a reaction that absorbs heat is endothermic; a reaction that gives off heat is exothermic. Now, feel the temperature of the test tube with your hand. 3. Pour off the liquid into a second test tube. Assuming the reaction is complete. What is this liquid composed of? Water and Glucose. What would happen if more liver were to be added to the liquid? More oxygen would be produced.
Test this and record the reaction rate. Reaction rate 0.
4. Add another 2 ml of hydrogen peroxide to the liver in the first tube. What is the reaction rate? 4. Is catalase reusable? Explain how you know.
Yes, it is reusable because catalase is an enzyme, and enzyme are molecules that speed up reactions and are not consumed. Part B
Procedure: Now test for the presence of catalase in tissues other than liver. Place 2 ml of hydrogen peroxide in each of 3 clean test tubes and then add each of the three test substances to the tubes. As each substance is added to the test tubes, record the reaction rate (0-5) for each tube.
Based on the observations, which tissues contained catalase? The chicken and potato.
Do some contain more than others? How can one tell? The rate of reaction.
1. Put a piece of liver into the bottom of a clean test tube and cover it with a small amount of water. Place this test tube in a boiling water for 5 minutes. 2. Remove the test tube from the hot water bath, allow it to air cool, then pour it out the water. Add 2 ml of hydrogen peroxide. CAUTION: Use a test-tube holder for hot test tubes.
What is the reaction rate for the boiled liver and peroxide? 3. Put equal quantities of liver into 2 clean test tubes and 1 ml H2O2 into 2 other test tubes. Put one test tube of liver and one of H2O2 into an ice bath. Place the other set in a warm water bath (not boiling)
After 3 minutes, pour each tube of H2O2 into the corresponding tube of liver and observe the reaction
What is the reaction rate for the cold liver/peroxide? 4.5.
What is the reaction rate for the warm liver/peroxide? 3. PART
1. Add 2 ml hydrogen peroxide to each of 5...
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