Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

3. Acids and Bases

Acids and Bases

Organic Chemistry

3. Acids and Bases

Acids and Bases

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Multiple Choice

In the context of acids and bases, which type of cell wall is thinner and does not retain the crystal violet stain in the Gram stain?

Gram-positive cell wall

Peptidoglycan-rich cell wall

Acid-fast cell wall

Gram-negative cell wall

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Verified step by step guidance

Understand the Gram staining process: Gram staining is a method used to classify bacterial species into two groups based on the physical properties of their cell walls. The process involves staining cells with crystal violet dye, followed by a counterstain, usually safranin.

Identify the characteristics of Gram-positive and Gram-negative bacteria: Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, which retains the crystal violet stain, appearing purple under a microscope. Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which does not retain the crystal violet stain and appears pink after counterstaining.

Recognize the role of peptidoglycan: Peptidoglycan is a polymer that provides structural strength to the bacterial cell wall. In Gram-positive bacteria, the thick peptidoglycan layer is responsible for retaining the crystal violet stain.

Consider the acid-fast cell wall: Acid-fast bacteria have a unique cell wall structure with a high lipid content, making them resistant to Gram staining. They require a different staining method, such as the Ziehl-Neelsen stain, to be visualized.

Conclude the characteristics of Gram-negative bacteria: Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, which prevents the retention of the crystal violet stain, resulting in a pink appearance after Gram staining.