Textbook Question
How will changing the conditions in an enzymatic reaction affect the rate of that reaction? Explain why in each case.
f. Decreasing the amount of substrate by half
Ch.19 Enzymes and Vitamins
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 19, Problem 91b
Apple slices and peeled potatoes rapidly brown in open air due to the presence of phenolases. Phenolases cause the oxidation of phenolic molecules like tyrosine to quinones, colored molecules responsible for the brown colors seen. An experiment comparing the time it took for a change to occur in the color of apple slices versus potato slices was done to test for phenolase activity. Then, a second experiment was done with new apple and potato slices with H2O2 measuring time until bubbles appeared.
b. Which sample contains more catalase? Why?
Verified step by step guidance1
Understand the role of catalase: Catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide (H₂O₂) into water (H₂O) and oxygen (O₂). The presence of bubbles in the experiment indicates the release of oxygen gas, which is a direct result of catalase activity.
Analyze the experiment: In the second experiment, both apple and potato slices were exposed to H₂O₂, and the time until bubbles appeared was measured. The sample that produced bubbles more quickly or in greater quantity has higher catalase activity.
Compare the samples: Observe the results of the experiment. If one sample (e.g., potato slices) produced bubbles faster or more vigorously than the other (e.g., apple slices), it indicates that the sample with faster or more vigorous bubbling contains more catalase.
Explain the reasoning: Catalase activity is directly proportional to the rate of bubble formation because the enzyme speeds up the breakdown of H₂O₂. Therefore, the sample with more catalase will show a quicker and more pronounced bubbling reaction.
Conclude based on observations: Based on the experimental data provided (e.g., time until bubbles appeared or the intensity of bubbling), determine which sample—apple or potato—contains more catalase and explain why using the principles of enzyme activity and reaction rates.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Phenolases
Phenolases are enzymes that catalyze the oxidation of phenolic compounds, such as tyrosine, into quinones. This process is responsible for the browning of fruits and vegetables when exposed to air. Understanding phenolase activity is crucial for analyzing how different samples, like apple and potato slices, react to oxidation and how this relates to their enzymatic content.
Catalase
Catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide (H2O2) into water and oxygen. It plays a vital role in protecting cells from oxidative damage by breaking down harmful peroxides. In the context of the experiment, measuring the time until bubbles appear indicates the presence and activity level of catalase in the samples, which helps determine which sample has a higher concentration of this enzyme.
Enzyme Activity Comparison
Comparing enzyme activity between different samples involves assessing how quickly a reaction occurs, often measured by the rate of product formation or substrate consumption. In this case, the time taken for visible reactions (browning or bubbling) provides insight into the relative amounts of phenolases and catalase present in apple and potato slices. This comparison is essential for understanding the biochemical properties of the samples.
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