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

Introduction to Eukaryotic Organelles

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Introduction to Eukaryotic Organelles

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Multiple Choice

Which of the following best describes a key difference between beta-keratin and alpha-keratin in eukaryotic cells?

Alpha-keratin contains more sulfur than beta-keratin.

Alpha-keratin is a carbohydrate, while beta-keratin is a lipid.

Beta-keratin is only found in mammals, while alpha-keratin is found in birds and reptiles.

Beta-keratin forms rigid structures like feathers and scales, while alpha-keratin is found in flexible structures like hair and skin.

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Verified step by step guidance

Understand the context of keratin proteins: Keratin is a structural protein found in eukaryotic cells, and it plays a key role in forming protective structures such as skin, hair, feathers, and scales.

Differentiate between alpha-keratin and beta-keratin: Alpha-keratin is primarily found in mammals and contributes to flexible structures like hair and skin. Beta-keratin, on the other hand, is found in birds and reptiles and contributes to rigid structures like feathers and scales.

Analyze the sulfur content: Alpha-keratin contains a higher proportion of sulfur due to the presence of cysteine residues, which form disulfide bonds. This is not the defining difference between alpha-keratin and beta-keratin, but it contributes to the flexibility of alpha-keratin.

Clarify the chemical composition: Both alpha-keratin and beta-keratin are proteins, not carbohydrates or lipids. This eliminates the option suggesting a difference in macromolecule type.

Conclude the key difference: The defining characteristic is the structural role of each type of keratin—alpha-keratin is associated with flexible structures, while beta-keratin is associated with rigid structures.