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

Intro to Organic Chemistry

Organic Chemistry

1. A Review of General Chemistry

Intro to Organic Chemistry

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Multiple Choice

Which scientist(s) used density gradient centrifugation to demonstrate semiconservative replication of DNA?

Pauling and Corey

Meselson and Stahl

Watson and Crick

Franklin and Wilkins

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Verified step by step guidance

Understand the concept of semiconservative replication: In semiconservative replication, each of the two strands of the DNA molecule serves as a template for the production of a complementary strand. This results in two DNA molecules, each with one old and one new strand.

Familiarize yourself with the technique of density gradient centrifugation: This method separates molecules based on their density by spinning them at high speeds in a centrifuge. Molecules move through a gradient of increasing density until they reach a point where their density matches that of the surrounding medium.

Identify the scientists associated with the discovery of semiconservative replication: Meselson and Stahl conducted experiments using density gradient centrifugation to demonstrate the semiconservative nature of DNA replication.

Review the historical experiment: Meselson and Stahl grew E. coli in a medium containing a heavy isotope of nitrogen (15N) and then switched to a medium with a lighter isotope (14N). They used density gradient centrifugation to separate DNA based on the different densities of the nitrogen isotopes incorporated into the DNA strands.

Analyze the results of the experiment: The results showed that after one round of replication, the DNA consisted of hybrid molecules (one strand with 15N and one with 14N), supporting the semiconservative model of DNA replication.