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

Carbohydrates

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Carbohydrates

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Problem L3.1

Textbook Question

The polysaccharide cellulose is not digestible by humans, as we lack the enzyme cellulase, which is required to break it down. Certain dietary supplements contain the enzyme cellulase and claim that being able to break down cellulose will help a person lose weight. But what do you think would happen if we could digest the cellulose we ate?

Verified step by step guidance

Understand the role of cellulose in the human diet: Cellulose is a polysaccharide made of glucose molecules linked by β-1,4-glycosidic bonds. Humans lack the enzyme cellulase, which is required to break these bonds, so cellulose passes through the digestive system as fiber, aiding in digestion and promoting gut health.

Consider the function of cellulase: If humans could digest cellulose using cellulase, the β-1,4-glycosidic bonds in cellulose would be broken down into glucose molecules, which could then be absorbed into the bloodstream and used as an energy source.

Analyze the potential impact on calorie intake: Since glucose is a source of calories, digesting cellulose would increase the caloric content of foods that contain cellulose. This could lead to an increase in energy intake rather than weight loss, unless the individual adjusts their overall diet to account for the additional calories.

Evaluate the claim of weight loss: The claim that digesting cellulose would help with weight loss is likely misleading. Instead of acting as a non-digestible fiber that aids in satiety and bowel health, cellulose would contribute to caloric intake, potentially leading to weight gain if not balanced with energy expenditure.

Reflect on the importance of fiber: Fiber, including cellulose, plays a critical role in maintaining digestive health, regulating blood sugar levels, and promoting a feeling of fullness. Digesting cellulose might reduce these benefits, which could negatively impact overall health.

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Key Concepts

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

Cellulose

Cellulose is a complex carbohydrate or polysaccharide that forms the structural component of the cell walls in green plants, algae, and some fungi. It is composed of long chains of glucose molecules linked by β-1,4-glycosidic bonds, making it resistant to digestion by humans due to the absence of the enzyme cellulase. While cellulose is not digestible, it serves as dietary fiber, promoting digestive health.

Enzymatic Digestion

Enzymatic digestion refers to the biochemical process where enzymes break down complex molecules into simpler ones, facilitating nutrient absorption. In the case of cellulose, the enzyme cellulase is necessary to hydrolyze the β-glycosidic bonds, allowing the body to utilize the glucose units. Without this enzyme, cellulose passes through the digestive system largely intact, contributing to fiber intake rather than energy.

Impact on Weight Loss

The claim that digesting cellulose could aid in weight loss hinges on the idea that breaking down this polysaccharide would provide additional calories. However, if humans could digest cellulose, it might lead to increased caloric intake without a corresponding increase in satiety, potentially resulting in weight gain rather than loss. Additionally, the role of fiber in promoting fullness and regulating appetite would be compromised.