Pre-Lab: Temperature and Enzymes
Problem How does temperature affect the rate of an enzyme-catalyzed reaction?
Materials raw liver, forceps, petri dish, dropper pipette, 1% hydrogen peroxide solution, 25-mL graduated cylinder, 50-mL beakers, puréed liver, filter paper disks, paper towels, timer or clock with a second hand, water baths, thermometers, beaker tongs
Lab Manual Chapter 2 Lab
Skills Focus Form a Hypothesis, Design an Experiment, Measure, Interpret Graphs
Connect to the Many chemical reactions in living organisms could not take place without enzymes. Enzymes catalyze the reactions that release energy from nutrients. They also catalyze the synthesis of the complex molecules that organisms need to grow and stay healthy. One factor that affects the action of enzymes is temperature. Think about why people store some foods in a refrigerator. The cold temperature limits the ability of enzymes to break down, or spoil, those foods.
Do high temperatures have the opposite effect on enzymes? Do they become more and more active as the temperature rises? In this lab, you will investigate the effect of temperature on an enzyme-catalyzed reaction.
Review Why do many reactions that occur in cells require enzymes? How do enzymes speed up chemical reactions?
Review Name three variables that can affect enzyme activity.
Use Analogies Use eggs and a frying pan on a stove as an analogy for reactants and an enzyme. Use the control knob on the stove burner as an analogy for how a variable can affect the action of an enzyme.
Preview the procedure in the lab manual.
Relate Cause and Effect How will you know that a chemical reaction is taking place in Part A? How will you know in Part B?
Control Variables In Part B of the lab, which variable will you manipulate? Which variable is the dependent variable?
Relate Cause and Effect How is the time required for the filter-paper disk to float related to the activity of the enzyme?
Visit Chapter 2 online to test yourself on chapter content and to find activities to help you learn.
Untamed Science Watch the Untamed Science crew find answers to the mystery of why water is such a special compound.
Art Review Learn about ionic and covalent bonding.
Art in Motion View an animation that shows the process of a salt crystal dissolving in water.
Data Analysis Analyze data that explains the physiological effects of low pH, and the ecological impact of acid rain.
Visual Analogy Compare enzymes and substrates to a lock and key.