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

Models of Enzyme Action

GOB Chemistry

19. Enzymes

Models of Enzyme Action

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4:11 minutes

Problem 87

Textbook Question

The enzyme trypsin catalyzes the breakdown of many structurally diverse proteins in foods. Does the induced-fit or lock-and-key model explain the action of trypsin better? Explain.

Verified step by step guidance

Understand the two models of enzyme action: The lock-and-key model suggests that the enzyme's active site is a perfect fit for the substrate, like a key fitting into a lock. The induced-fit model proposes that the enzyme's active site undergoes a conformational change to better fit the substrate upon binding.

Consider the nature of trypsin: Trypsin is a protease enzyme that catalyzes the breakdown of proteins by cleaving peptide bonds. It interacts with a wide variety of structurally diverse proteins, which implies flexibility in its binding mechanism.

Evaluate the lock-and-key model: This model assumes a rigid active site that matches the substrate exactly. Given the structural diversity of proteins trypsin acts on, this model may not fully explain its mechanism.

Evaluate the induced-fit model: This model accounts for flexibility in the enzyme's active site, allowing it to adapt to different substrates. This adaptability aligns well with trypsin's ability to catalyze reactions for various proteins.

Conclude that the induced-fit model better explains the action of trypsin, as it accommodates the enzyme's ability to interact with diverse protein structures by adjusting its active site to fit each substrate.

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Key Concepts

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

Induced-Fit Model

The induced-fit model of enzyme action suggests that the enzyme's active site is flexible and can change shape to better fit the substrate upon binding. This model emphasizes the dynamic nature of enzyme-substrate interactions, allowing for a more precise fit that enhances catalytic efficiency. It accounts for the adaptability of enzymes to various substrates, making it particularly relevant for enzymes like trypsin that act on diverse protein structures.

Lock-and-Key Model

The lock-and-key model posits that enzymes and substrates fit together in a rigid, complementary manner, much like a key fits into a lock. This model implies that the enzyme's active site is specifically shaped to match a particular substrate, which limits the enzyme's ability to accommodate variations in substrate structure. While this model provides a straightforward explanation of enzyme specificity, it may not fully capture the complexities of enzymes like trypsin that interact with a wide range of protein substrates.

Enzyme Specificity

Enzyme specificity refers to the ability of an enzyme to selectively catalyze a particular reaction or act on specific substrates. This characteristic is crucial for understanding how enzymes like trypsin function in the digestive system, where they break down proteins into smaller peptides. The degree of specificity can influence whether the induced-fit or lock-and-key model better explains the enzyme's action, as trypsin's ability to adapt to various protein structures suggests a more flexible interaction.

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What kind of interaction attracts the cofactor Mg²⁺ and ATP to each other? (Hint: Look at the structure of the phosphate group.)

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Match the terms (1) active site, (2) lock-and-key model, and (3) induced-fit model with the following descriptions:

a. the portion of an enzyme where catalytic activity occurs

b. the active site adapts to the shape of a substrate

c. the active site has a rigid shape

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Do the amino acids that are in the active site of an enzyme have to be near each other in the enzyme’s primary structure? If no, explain.

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The enzyme sucrase catalyzes the hydrolysis of the disaccharide sucrose but not the disaccharide lactose. Does the induced-fit or lock-and-key model explain the action of sucrase better? Explain.

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Open Question

Match each model with correct descriptions: (a) Induced fit model, (b) Lock and key model.

________ Active site undergoes changes in shape during reaction.

________ Enzyme is specific only to one substrate.

________ Shape of active site is similar to that of substrate.

________ Enzyme model that more accurately describes substrate-enzyme interactions.

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Textbook Question

What is the difference between the lock-and-key model of enzyme action and the induced-fit model?