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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

Base Pairing

Organic Chemistry

34. Nucleic Acids

Base Pairing

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Multiple Choice

Why do adenine and thymine pair up in DNA?

They form three hydrogen bonds with each other.

They form two hydrogen bonds with each other.

They have complementary shapes that allow ionic bonding.

They are both purines, which allows them to pair.

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Verified step by step guidance

Understand the structure of DNA: DNA is composed of two strands forming a double helix, with each strand consisting of a sugar-phosphate backbone and nitrogenous bases.

Identify the nitrogenous bases: In DNA, there are four types of nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).

Recognize base pairing rules: Adenine pairs with thymine, and cytosine pairs with guanine. This is known as complementary base pairing.

Explore hydrogen bonding: Adenine and thymine pair through hydrogen bonds. Specifically, they form two hydrogen bonds, which is a key factor in their pairing.

Clarify the role of molecular structure: The specific shapes and chemical structures of adenine and thymine allow them to form these hydrogen bonds, ensuring the stability of the DNA double helix.