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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5:32 minutes

Problem 96

Textbook Question

Problems 10.94 and 10.95 both mention enzymes that hydrolyze peptide bonds. How do you account for the fact that pepsin has a high catalytic activity at pH 1.5 but chymotrypsin has very little activity at pH 1.5?

Verified step by step guidance

Understand the concept of enzyme activity and how it is influenced by pH. Enzymes are proteins that act as catalysts, and their activity depends on the structure of their active site, which can be affected by pH levels.

Recognize that pepsin and chymotrypsin are enzymes that hydrolyze peptide bonds, but they function optimally at different pH levels due to their distinct structures and environments in the body.

Note that pepsin is active in the stomach, where the pH is highly acidic (around 1.5). Its structure is adapted to function in this environment, maintaining its active site configuration at low pH levels.

Understand that chymotrypsin operates in the small intestine, where the pH is closer to neutral (around 7-8). At a pH of 1.5, the structure of chymotrypsin's active site is disrupted, leading to very little catalytic activity.

Conclude that the difference in catalytic activity at pH 1.5 is due to the specific adaptations of each enzyme to their physiological environments, with pepsin being suited for acidic conditions and chymotrypsin for neutral conditions.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Enzyme Catalysis

Enzyme catalysis refers to the process by which enzymes accelerate chemical reactions. Enzymes lower the activation energy required for reactions, allowing them to occur more rapidly. The efficiency of an enzyme is influenced by various factors, including pH, temperature, and substrate concentration. Understanding how these factors affect enzyme activity is crucial for analyzing their function in biological systems.

pH and Enzyme Activity

pH is a measure of the acidity or alkalinity of a solution, which can significantly impact enzyme activity. Each enzyme has an optimal pH range where it functions best; deviations from this range can lead to decreased activity or denaturation. For instance, pepsin is adapted to function in the highly acidic environment of the stomach (pH 1.5), while chymotrypsin operates optimally in a more neutral pH, typically around 7.5, affecting their catalytic activities in different environments.

Specificity of Enzymes

Enzymes exhibit specificity, meaning they are designed to catalyze specific reactions or act on particular substrates. This specificity is determined by the enzyme's active site structure, which complements the substrate's shape and chemical properties. Pepsin and chymotrypsin, while both proteolytic enzymes, have evolved to function optimally in different environments and with different substrates, which explains their varying activities at pH 1.5.

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Textbook Question

How would the following changes affect enzyme activity for an enzyme whose optimal conditions are normal body temperature and physiological pH?

a. raising the temperature from 37 °C to 60 °C

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Textbook Question

The enzyme urease functions in the body to catalyze the formation of ammonia and carbon dioxide from urea as shown:

Describe what effect the following changes would have on the rate of this reaction assuming a steady state has been reached:

a. adding excess urea

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Textbook Question

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

a. increasing the concentration of proteins

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Textbook Question

c. running the reaction at 0 °C

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Textbook Question

Meats spoil due to the action of enzymes that degrade the proteins. Fresh meats can be preserved for long periods of time by freezing them. Explain how freezing meats works to prevent spoilage.

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Textbook Question

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be given prior to consuming dairy products. (16.4, 16.5)

b. What might happen to the enzyme if the Lactaid were stored at 55 °C?

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Multiple Choice

Pepsin, a peptidase that hydrolyzes proteins, functions in the stomach at an optimum pH of 1.5 to 2.0.

Which of the following would cause an increase in its activity?

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Multiple Choice

Sucrase has an optimum pH range of 4.5 – 7.0. Which of the following statements is true?

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