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 Chemical Bonding

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Introduction to Chemical Bonding

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Multiple Choice

What happens to the gram-positive cell wall during the decolorization step of the Gram staining process?

The thick peptidoglycan layer retains the crystal violet-iodine complex.

The outer membrane dissolves, allowing the dye to escape.

The cell wall absorbs the safranin counterstain.

The cell wall becomes completely decolorized.

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Verified step by step guidance

Understand the structure of a gram-positive cell wall: It consists of a thick peptidoglycan layer, which is crucial for retaining stains during the Gram staining process.

Review the Gram staining process: It involves four main steps - application of crystal violet (primary stain), iodine treatment (mordant), alcohol wash (decolorization), and safranin (counterstain).

Focus on the decolorization step: During this step, alcohol or acetone is applied to the cells. In gram-positive bacteria, the thick peptidoglycan layer retains the crystal violet-iodine complex, preventing decolorization.

Contrast with gram-negative bacteria: In gram-negative bacteria, the alcohol dissolves the outer membrane and the thin peptidoglycan layer does not retain the crystal violet-iodine complex, leading to decolorization.

Conclude with the effect of the safranin counterstain: After decolorization, safranin is applied. Gram-positive cells remain purple because they retain the crystal violet, while gram-negative cells take up the safranin and appear pink.