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

Intro to Nucleic Acids

Organic Chemistry

34. Nucleic Acids

Intro to Nucleic Acids

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Multiple Choice

Which of the following techniques allows for DNA fragments to be separated by size?

Gel electrophoresis

NMR spectroscopy

Mass spectrometry

X-ray crystallography

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Verified step by step guidance

Begin by understanding the purpose of each technique listed. Gel electrophoresis is used to separate DNA fragments based on size, while NMR spectroscopy, mass spectrometry, and X-ray crystallography serve different purposes in molecular analysis.

Gel electrophoresis involves applying an electric field to a gel matrix, causing DNA fragments to migrate through the gel. Smaller fragments move faster and further than larger ones, allowing for separation by size.

Consider the principle of gel electrophoresis: DNA is negatively charged due to its phosphate backbone, and when an electric field is applied, it moves towards the positive electrode.

The gel matrix, often made of agarose, acts as a sieve, where the pore size affects the movement of DNA fragments. Smaller fragments navigate through the pores more easily than larger ones.

Review the other techniques: NMR spectroscopy is used for determining molecular structure, mass spectrometry for measuring mass-to-charge ratios, and X-ray crystallography for elucidating crystal structures. None of these are used for separating DNA fragments by size.