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

34. Nucleic Acids

DNA Double Helix

Organic Chemistry

34. Nucleic Acids

DNA Double Helix

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Multiple Choice

How does the data from X-ray diffraction support Watson and Crick's model of the DNA double helix?

It reveals that DNA is a linear molecule without any helical structure.

It indicates that DNA is a single-stranded molecule.

It shows that DNA is composed of two strands forming a double helix.

It suggests that DNA is composed of three strands twisted together.

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Verified step by step guidance

X-ray diffraction is a technique used to study the structure of crystalline materials by observing the patterns formed when X-rays are scattered by the atoms within the material.

Rosalind Franklin's X-ray diffraction images of DNA, particularly the famous 'Photo 51', provided crucial evidence for the helical structure of DNA.

The diffraction pattern showed a characteristic 'X' shape, which is indicative of a helical structure. This pattern suggested that the DNA molecule was not linear or single-stranded, but rather had a repeating helical form.

The spacing of the spots in the diffraction pattern indicated that the helix had a consistent diameter, supporting the idea of two strands winding around each other in a regular manner.

Watson and Crick used this data to propose their model of the DNA double helix, where two strands are held together by base pairs, forming a stable and uniform structure.