Understanding Chemical Reactions and Enzymes (Answers)

Understanding Chemical Reactions and Enzymes – Group Worksheet Background Enzymes are an important group of macromolecules that can help speed up chemical reactions. Each enzyme can only help a specific chemical reaction. Today, you will learn about chemical reactions and how enzymes can speed them up. 1. In the sample chemical equation below: highlight the reactants and the products C6H12O6 + 6O2 🡪6H2O + 6CO2+ energy 2. What do the reactants of a chemical reaction need in order to change and become products during a chemical reaction? rearrange and form new bonds to make the products. 3. Explain the label for the x-axis. In other words, what does “Progress of reaction” mean? The time it takes for the reaction to begin 4. In the graph titled, "Energy in a chemical reaction,” what does Ea refer to? The E stands for the amount of excess energy used 5. What is activation energy? The activation energy is the amount of energy needed to start the process 6. What type of macromolecule are enzymes? nucleic acids 7. In the graph titled “Activation Energy of a Chemical Reaction with and without an Enzyme,” which graph shows the chemical reaction without an enzyme? Circle: [higher] or [lower] The red line is higher than the activation with an enzyme. 8. In the graph, which graph shows the chemical reaction with an enzyme? Circle: [higher] or [lower] The blue line is lower 9. Comparing the two graphs, list at least two similarities between the graph of the chemical reaction with an enzyme and the graph of the chemical reaction without an enzyme. the same reaction and same energy. 10. Comparing the two graphs, identify one difference between the graphs of the chemical reaction with an enzyme and the graph of the chemical reaction without an enzyme. less activation energy 11. What happened to the activation energy of the chemical reaction when an enzyme was added? it decreased Use Diagram #1 to answer the following questions. 12. Draw the enzyme. (“Insert” -> “Drawing”) 13. What part of the enzyme does the substrate connect to? the active site 14. The diagram shows a chemical reaction, with reactant(s) changing into product(s). Draw the reactant(s). 15. Draw the product(s). (“Insert” -> “Drawing”) 16. Use the shapes to write out the chemical equation for the reaction. HINT: Refer to Resource #1. Use Diagram #2 to answer the following questions. 17. Draw the enzyme. (“Insert” -> “Drawing”) 18. Use the shapes to write out the chemical equation for the reaction. HINT: Refer to Resource #1. 19. How can you tell which shape in each of the diagrams is the enzyme? HINT: What does NOT change shape before and after a chemical reaction? 20. Explain the label for the y-axis. In other words, what does “Rate of reaction” mean? 21. At what temperature do most human enzymes work the best? 22. What do you think is the average “body temperature” of thermophilic bacteria? Explain your answer. 23. Would pepsin be able to break down proteins that make it to the small intestines? Explain your answer. HINT: Consider the optimal pH for pepsin and the pH of the small intestines. Understanding Chemical Reactions and Enzymes Resource #1: Understanding Chemical Reactions Background Energy can be stored or released by chemical reactions. A chemical reaction is a process during which molecules are changed. The chemical bonds between atoms of the starting molecules are broken and new ones are formed, producing one or more new molecules. The reactants are the starting materials for a chemical reaction. The products are the new molecules that form from a chemical reaction. Scientists can show chemical reactions using chemical equations. The general form of a chemical equation is: Reactants Products The reactants are always on the left side of the equation, and the products are on the right side. The arrow shows that the reactants have changed into the products. The following is an example of a chemical equation you will be learning more about: Key: C6H12O6 = Glucose O2 = Oxygen H2O = Water CO2 = Carbon Dioxide C6H12O6 + 6O2 🡪6H2O + 6CO2+ energy In order for a chemical reaction to occur, the reactants need to get enough energy to be able to break and reform the bonds between their atoms. This amount of energy they need is called the activation energy (Ea). The graph below shows the change in energy during a chemical reaction. The reactants begin with a certain amount of energy. They need to gain the additional amount of activation energy in order to change into the products. Energy in a Chemical Reaction En erg y in mo lec ule s Progress of reaction Understanding Chemical Reactions and Enzymes Resource #2: Activation energy with or without enzymes Activation Energy of a Chemical Reaction with and without an Enzyme Helpful Hint ✔ Enzymes are a special type of macromolecule that can help speed up chemical reactions. ✔ They speed up reactions by lowering the amount of activation energy a group of reactants needs in order for a chemical reaction to occur. ✔ Most enzymes are types of proteins. Understanding Chemical Reactions and Enzymes Resource #3: How do enzymes work? Background The diagrams below show how two different enzymes work to decrease the activation energy of a chemical reaction. Diagram #1: Diagram #2: Reactants A B Product AB Helpful Hints: ✔ A substrate is the reactant that comes into contact with an enzyme at its active site. ✔ An enzyme and its substrate match in shape like a lock and key, but are NOT a perfect match. ✔ The enzyme helps the reactants of a chemical reaction make the necessary changes to form into the products of a chemical reaction. ✔ The shape of an enzyme DOES NOT CHANGE after a chemical reaction. Understanding Chemical Reactions and Enzymes Resource #4: Factors that Affect Enzyme Activity Background ● The first graph shows how fast different chemical reactions happen with different enzymes at different temperatures. ● The second graph shows how fast different chemical reactions happen with two different enzymes, trypsin and pepsin, at different pH’s. Helpful Hints: ✔ Average human body temperature is 37°C. ✔ Thermophilic bacteria are bacteria found in hot springs. ✔ The pH of a human stomach can range from 1.0 to 5.0. ✔ The pH of the small intestines is around 8.0. ✔ Pepsin is an enzyme that helps to speed up the chemical reactions that break the bonds between the amino acids in certain proteins. ✔ Trypsin is an enzyme that helps to speed up the chemical reactions that break down the bonds between the amino acids in certain proteins.