Appendix G Instructor’s Answer Guide Pre-lab Questions 1. What type of molecule is an enzyme?
Enzymes are typically protein molecules that are made up of amino acids. There are some enzymes that are made of nucleic acids as well. 2. Why is an enzyme’s shape important to its function?
An enzyme’s active site needs to be the right shape so that the substrate molecule can fit into it properly. The primary structure of a protein determines its secondary, tertiary, and if applicable, quaternary structure. The chemical groups of the amino acids interact forming hydrogen, ionic, covalent, and Van der Waals interactions to create a specific shape. The R groups of the amino acids in the active site are the most important amino acids in an enzyme. This is because they are the chemical groups responsible for shifting electron densities to make or break bonds within the substrate. If these amino acids are not in the correct orientation, the active site will not be able to catalyze the reaction. 3. How does an enzyme speed up chemical reactions?
APPENDIX G
Enzymes speed up chemical reactions by positioning the substrate molecule(s), which lowers the energy of activation. The energy of activation is the amount of energy that is required to bring the substrate molecule into the transition state (unstable intermediate). An enzyme stabilizes the transition state and lowers the amount of energy of the transition state molecule. This will cause the reaction to occur faster because less energy is required for each substrate molecule to be converted to product. 4. What is the name of the enzyme involved in this laboratory experiment?
Cellobiase (a type of cellulase) or beta-glucosidase 5. What is one practical, industrial application of this enzyme?
Production of cellulosic ethanol for fuel 6. What is the natural product of this enzyme?
Glucose 7. What is the natural substrate of this enzyme?
Cellobiose (a dissacharide) 8. How will you be able to determine the amount of product that is produced at each time period?
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