Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

19. Enzymes

Factors Affecting Enzyme Activity

GOB Chemistry

19. Enzymes

Factors Affecting Enzyme Activity

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2:26 minutes

Problem 91b

Textbook Question

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 guidance

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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Related Practice

Textbook Question

What general effects would you expect the following changes to have on the rate of an enzyme-catalyzed reaction for an enzyme that has its maximum activity at body temperature (about 37°C)?

a. Raising the temperature from 37°C to 70°C

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Textbook Question

What general effects would you expect the following changes to have on the rate of an enzyme-catalyzed reaction for an enzyme that has its maximum activity at body temperature (about 37°C)?

c. Adding an organic solvent, such as methanol

693

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Textbook Question

What general effects would you expect the following changes to have on the rate of an enzyme-catalyzed reaction for an enzyme that has its maximum activity at body temperature (about 37°C)?

c. Adding an oxidizing agent, such as hydrogen peroxide

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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

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Textbook Question

Trypsin, a peptidase that hydrolyzes polypeptides, functions in the small intestine at an optimum pH of 7.7 to 8.0. How is the rate of a trypsin-catalyzed reaction affected by each of the following conditions?

b. running the reaction at 75 °C

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Textbook Question

Pepsin, a peptidase that hydrolyzes proteins, functions in the stomach at an optimum pH of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?

a. changing the pH to 5.0

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Textbook Question

The following graph shows the activity versus pH curves for pepsin, sucrase, and trypsin. Estimate the optimum pH for each.

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Textbook Question

Refer to the graph in problem 16.45 to determine if the reaction rate in each condition will be at the optimum rate or not.

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a. trypsin, pH 5.0