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

1. A Review of General Chemistry

Sigma and Pi Bonds

Organic Chemistry

1. A Review of General Chemistry

Sigma and Pi Bonds

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Multiple Choice

Alpha-helices and beta-pleated sheets are formed by hydrogen bonds between which of the following components?

Hydrogen atoms in the side chains

Nitrogen and oxygen atoms in the backbone

Carbon atoms in the backbone

Sulfur atoms in the side chains

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Verified step by step guidance

Understand the structure of proteins: Proteins are made up of amino acids linked together in a chain, forming a polypeptide backbone with side chains (R groups) extending from it.

Identify the components involved in secondary structures: Alpha-helices and beta-pleated sheets are types of secondary structures in proteins, stabilized by hydrogen bonds.

Focus on the backbone interactions: In these structures, hydrogen bonds form between the carbonyl oxygen (C=O) and the amide hydrogen (N-H) in the backbone of the polypeptide chain.

Clarify the role of side chains: While side chains can influence the overall shape and function of the protein, they are not directly involved in the hydrogen bonding that stabilizes alpha-helices and beta-pleated sheets.

Conclude with the correct components: The hydrogen bonds that stabilize these secondary structures occur between the nitrogen and oxygen atoms in the backbone, not the side chains.