Name Date Period Enzyme Reaction Rates Using TOOTHPICKASE INTRODUCTION: Enzymes are proteins that are used as catalysts in biochemical reactions. A catalyst is a factor that controls the rate of a reaction without itself being used up. In biological systems, enzymes are used to speed up the rate of a chemical reaction. However, there are a number of factors that can affect the rate of an enzyme-facilitated reaction, in addition to the presence of the enzyme, amongst them are: 1. The concentration of the enzyme 2. The concentration of the substrate 3. The temperature 4. The ph 5. Salt concentration Enzymes have optimal conditions in which they work best. If the enzyme is in an environment that is outside of it s optimal conditions, it will not work as efficiently or possibly not work at all. When environmental conditions are too far out of the enzyme s optimal conditions, the enzyme might become denatured. This means that the enzyme will lose its 3-dimensional functional shape and will no longer fit with the substrate on which it works. Here is a set of quick activities designed to simulate how temperature and denaturing an enzyme affect enzyme function. In the activities that follow:! One person s fingers are the enzyme TOOTHPICKASE! The toothpicks are the SUBSTRATE! Toothpickase is a DIGESTIVE ENZYME. It breaks down toothpicks into two units. To hydrolyse the toothpick, place a toothpick between the thumb and the first finger of each hand. Break the toothpick in two pieces. Pre-Lab Quick Check: 1. What is an enzyme? 2. What represents the enzyme in this lab? 3. What is a substrate? 4. What represents the substrate in this lab? 5. What represents the product in this lab? 1
PROCEDURE: Part A: RATE OF PRODUCT FORMATION IN AN ENZYME-CATALYZED REACTION 1. Select 80 toothpicks and place them on your paper plate. 2. In your group of three, one person will be the timer, one will count and record the data, and the third person will be the enzyme, toothpickase. Record roles below: a. Timer = b. Counter/Data Recorder= c. Toothpickase = YOU MAY NOT SWITCH ROLES DURING THIS LAB 3. The enzyme is to break the toothpicks without looking at the plate and all of the products ( broken toothpicks ) must remain on the plate. Remember, toothpicks can only be digested once; do not break toothpicks already broken! You may only break one toothpick at a time. 4. The experiment is conducted in 10 second intervals. The timer calls out start and then marks each 10 second interval for 100 seconds. The recorder tallies the cumulative number of toothpicks broken as each interval is announced by the timer. 5. Graph the results. PART B: EFFECT OF TEMPERATURE ON REACTION RATE 1. Remove the broken toothpicks from the plate (please don t throw out the un-broken ones!). Place 80 new toothpicks on your plate. 2. Place your hands in a pail of iced water for a minute before beginning your trial. Be sure to dry your hands off quickly with a paper towel before you begin breaking the toothpicks. 3. The enzyme is to break the toothpicks without looking at the plate and all of the products ( broken toothpicks ) must remain on the plate. Remember, toothpicks can only be digested once; do not break toothpicks already broken! You may only break one toothpick at a time. 4. The experiment is conducted in 10 second intervals. The timer calls out start and then marks each 10 second interval for 100 seconds. The recorder tallies the cumulative number of toothpicks broken as each interval is announced by the timer. 5. Graph the results. 2
PART C: EFFECT OF DENATURING AN ENZYME 1. Remove the broken toothpicks from the plate (please don t throw out the un-broken ones!). Place 80 new toothpicks on your plate. 2. Your teacher will give you instructions for how to denature toothpickase. 3. The enzyme is to break the toothpicks without looking at the plate and all of the products ( broken toothpicks ) must remain on the plate. Remember, toothpicks can only be digested once; do not break toothpicks already broken! You may only break one toothpick at a time. 4. The experiment is conducted in 10 second intervals. The timer calls out start and then marks each 10 second interval for 100 seconds. The recorder tallies the cumulative number of toothpicks broken as each interval is announced by the timer. 5. Graph the results. When you have graphed all three lines, ask your teacher to initial your graph. YOU WILL NOT GET CREDIT FOR YOUR GRAPH UNLESS YOUR TEACHER INITIALS IT. 3
Name Date Period Toothpickase Lab Data Sheet Part A: RATE OF PRODUCT FORMATION IN AN ENZYME-CATALYZED REACTION Time (seconds) 0 10 20 30 40 50 60 70 (1 min 10 sec) 80 (1 min 20 sec) 90 (1 min 30 sec) 100 (1 min 40 sec) TOTAL number of toothpicks broken PART B: EFFECT OF TEMPERATURE ON REACTION RATE Time (seconds) 0 10 20 30 40 50 60 70 (1 min 10 sec) 80 (1 min 20 sec) 90 (1 min 30 sec) 100 (1 min 40 sec) TOTAL number of toothpicks broken 4
PART C: EFFECT OF DENATURING AN ENZYME Time (seconds) 0 10 20 30 40 50 60 70 (1 min 10 sec) 80 (1 min 20 sec) 90 (1 min 30 sec) 100 (1 min 40 sec) TOTAL number of toothpicks broken Directions: Create a graph of the data you collected from Part A, Part B and Part C. Title Teacher Initials 5
Lab Questions 1. Describe how an enzyme works (in detail!). Use the following words in your answer: enzyme, substrate, product, and active site. 2. Which part of your experiment (part A, B, or C) represented the control group and why? 3. Use the words increases, decreases, or stays the same to fill in the blanks.! During an enzymatic reaction the amount of substrate as the reaction progresses.! During an enzymatic reaction the amount of product as the reaction progresses.! During an enzymatic reaction the amount of enzyme as the reaction progresses. 4. Review your data from Part B of your lab. a. How did lowering the temperature of your enzyme affect the rate of reaction? b. Explain what would happen to an enzyme-facilitated reaction if temperature were increased. Be sure to include the effect if temperature were increased to 100 degrees Celsius. c. What do you speculate is the optimal temperature for enzymes functioning in the human body? 5. Review your data from part C of the lab. a. In part C of your lab, you changed the shape of the enzyme Toothpickase. What is the term for changing the shape of the enzyme? b. How did denaturing your enzyme affect the rate of reaction? c. Name three conditions that would lead to an enzyme becoming denatured. 6
6. One condition that can affect the rate of reaction of an enzyme is ph. Take a look at the experiment below and answer the questions. Experiments were designed to study the effect of ph on the rate of enzyme action for 2 different enzymes found in animals, Enzyme A and Enzyme B. Enzyme A is found in the stomach and digests meats. Enzyme B is found in the intestine and digests fats. Use the graph to answer the following questions. a. At what ph is Enzyme A working at its maximum rate? b. Since Enzyme A is found in the stomach, what is the probable ph of the stomach? c. At what PHs does Enzyme A not work? d. At what ph is Enzyme B working at its maximum rate? e. Since Enzyme B is found in the intestine, what is the probable ph of the intestine? Teacher Initials (Your teacher will initial your paper when you complete your questions) 7