Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

2. Cell Chemistry & Cell Components

Proteins

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Proteins

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Problem 10

Textbook Question

An enzyme is a:
a. biological catalyst that increases the concentration of the products.
b. biological catalyst that increases the concentration of the reactants.
c. chemical that is used in a reaction, after which it can no longer be used by the cell.
d. biological catalyst that works by bringing its substrates closer to their transition states.

Verified step by step guidance

Understand the definition of an enzyme: An enzyme is a biological catalyst, meaning it speeds up chemical reactions in the body without being consumed in the process.

Review the role of a catalyst: Catalysts work by lowering the activation energy required for a reaction to occur, making it easier for reactants to reach their transition state and form products.

Analyze the options provided: Option (a) suggests enzymes increase product concentration, which is incorrect because enzymes do not alter the equilibrium of a reaction. Option (b) suggests enzymes increase reactant concentration, which is also incorrect for the same reason. Option (c) states enzymes are used up in reactions, which contradicts their role as reusable catalysts.

Focus on option (d): This option states that enzymes work by bringing substrates closer to their transition states, which aligns with the mechanism of action of enzymes. Enzymes bind to substrates at their active sites, stabilizing the transition state and facilitating the reaction.

Conclude that the correct answer is the option that accurately describes the function of enzymes as biological catalysts that assist substrates in reaching their transition states without being consumed in the reaction.

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Key Concepts

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

Enzymes as Biological Catalysts

Enzymes are proteins that act as biological catalysts, meaning they accelerate chemical reactions without being consumed in the process. They lower the activation energy required for reactions, allowing them to occur more quickly and efficiently. This catalytic function is crucial for various biological processes, including metabolism and DNA replication.

Substrate and Active Site Interaction

The active site of an enzyme is a specific region where substrates bind. This interaction is highly specific, often described by the 'lock and key' model, where the enzyme's active site (the 'lock') is shaped to fit a particular substrate (the 'key'). This proximity facilitates the transition state, leading to the formation of products more efficiently.

Transition State Theory

Transition state theory posits that during a chemical reaction, reactants must reach a high-energy state known as the transition state before converting into products. Enzymes stabilize this transition state, effectively lowering the energy barrier and increasing the likelihood of the reaction proceeding. This concept is fundamental to understanding how enzymes enhance reaction rates.