Textbook Question
Identify each of the following bases as a purine or a pyrimidine:
a. guanine
Ch.17 Nucleic Acids and Protein Synthesis
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353
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Table of contents
- Ch.1 Chemistry in Our Lives11
- Ch.2 Chemistry and Measurements80
- Ch.3 Matter and Energy54
- Ch.4 Atoms and Elements51
- Ch.5 Nuclear Chemistry42
- Ch.6 Ionic and Molecular Compounds57
- Ch.7 Chemical Quantities and Reactions41
- Ch.8 Gases29
- Ch.9 Solutions51
- Ch.10 Acids and Bases and Equilibrium65
- Ch.11 Introduction to Organic Chemistry: Hydrocarbons78
- Ch.12 Alcohols, Thiols, Ethers, Aldehydes, and Ketones83
- Ch.13 Carbohydrates54
- Ch.14 Carboxylic Acids, Esters, Amines, and Amides90
- Ch.15 Lipids61
- Ch.16 Amino Acids, Proteins, and Enzymes84
- Ch.17 Nucleic Acids and Protein Synthesis83
- Ch.18 Metabolic Pathways and ATP Production67
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 17, Problem 1b
Identify each of the following bases as a purine or a pyrimidine:
b. 
Verified step by step guidance1
Understand the difference between purines and pyrimidines: Purines are larger, double-ring structures, while pyrimidines are smaller, single-ring structures. Examples of purines include adenine (A) and guanine (G), while pyrimidines include cytosine (C), thymine (T), and uracil (U).
Examine the structure of the base provided in the image. Look for the number of rings in the structure: a single ring indicates a pyrimidine, while two fused rings indicate a purine.
Identify any functional groups or atoms attached to the rings. For example, purines often have amine groups or oxygen atoms attached to their double-ring structure, while pyrimidines may have similar groups attached to their single ring.
Compare the structure in the image to known examples of purines and pyrimidines to determine its classification.
Conclude whether the base in the image is a purine or a pyrimidine based on its structural characteristics and the number of rings.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Purines
Purines are one of the two classes of nitrogenous bases found in nucleic acids, characterized by a double-ring structure. The two primary purines in DNA and RNA are adenine (A) and guanine (G). Their structure allows them to form hydrogen bonds with complementary pyrimidines, playing a crucial role in the formation of the DNA double helix and RNA structures.
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Nitrogenous Bases Example 1
Pyrimidines
Pyrimidines are the second class of nitrogenous bases, distinguished by a single-ring structure. The main pyrimidines in nucleic acids are cytosine (C), thymine (T), and uracil (U). These bases pair with purines to stabilize the nucleic acid structure, contributing to the genetic code and the overall function of DNA and RNA.
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Base Pairing
Base pairing refers to the specific hydrogen bonding between purines and pyrimidines in nucleic acids, which is essential for the stability and integrity of DNA and RNA. In DNA, adenine pairs with thymine, while guanine pairs with cytosine. In RNA, adenine pairs with uracil instead of thymine. This complementary pairing is fundamental for processes such as DNA replication and transcription.
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