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

3. Energy & Cell Processes

Enzyme Binding Factors

Anatomy & Physiology

3. Energy & Cell Processes

Enzyme Binding Factors

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1:26 minutes

Problem 13

Textbook Question

Your body makes NAD+ and FAD from two B vitamins, niacin and riboflavin. The Recommended Dietary Allowance is 20 mg for niacin and 1.7 mg for riboflavin. These amounts are thousands of times less than the amount of glucose your body needs each day to fuel its energy needs. Why is the daily requirement for these vitamins so small?

Verified step by step guidance

Understand the role of NAD+ and FAD in cellular metabolism: NAD+ (Nicotinamide adenine dinucleotide) and FAD (Flavin adenine dinucleotide) are coenzymes that play crucial roles in redox reactions, particularly in the processes of glycolysis, the citric acid cycle, and oxidative phosphorylation.

Recognize the function of coenzymes: Coenzymes like NAD+ and FAD are not consumed in the reactions they facilitate. Instead, they act as carriers of electrons and protons, allowing them to be reused multiple times in metabolic pathways.

Consider the efficiency of coenzyme recycling: Since NAD+ and FAD are regenerated during metabolic processes, the body does not need large amounts of these vitamins to maintain adequate levels of the coenzymes.

Acknowledge the catalytic nature of vitamins: Vitamins such as niacin and riboflavin, which are precursors to NAD+ and FAD, function in small amounts because they are not used up in the reactions they catalyze. This catalytic property means that a small amount can facilitate a large number of reactions.

Relate to the body's energy needs: While glucose is a primary energy source and required in large amounts, the vitamins needed to process glucose into usable energy are required in much smaller quantities due to their role as catalysts and their ability to be recycled.

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Key Concepts

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

Vitamin Function

Vitamins are organic compounds that are essential for various biochemical functions in the body. Niacin (Vitamin B3) and riboflavin (Vitamin B2) play crucial roles in energy metabolism by serving as precursors for coenzymes NAD+ and FAD, which are vital for cellular respiration and energy production. Their small daily requirements reflect their role as catalysts in metabolic pathways rather than as primary energy sources.

Energy Metabolism

Energy metabolism refers to the biochemical processes that convert nutrients into energy. Glucose is the primary energy source for the body, providing the bulk of energy needed for daily activities. In contrast, NAD+ and FAD derived from niacin and riboflavin facilitate the breakdown of glucose and other substrates, highlighting that while vitamins are crucial, they do not provide energy directly.

Recommended Dietary Allowance (RDA)

The Recommended Dietary Allowance (RDA) is a guideline that indicates the daily intake level of essential nutrients sufficient to meet the needs of most healthy individuals. The RDA for niacin and riboflavin is low because these vitamins are required in small amounts to support their roles in metabolic processes, emphasizing that the body can function effectively with minimal quantities of these nutrients compared to macronutrients like carbohydrates.