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A Visual Guide to Purines and Pyrimidines

From Laura Klappenbach, About.com

Nucleic acids such as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) provide organisms with a means for storing and transmitting genetic information. These linear, unbranched biopolymers are made up of building blocks called nucleotides.

Nucleotides are the building blocks that, when combined, form nucleic acids. Nucleotides are made up of a pentose (five-carbon sugar), 1-3 phosphate groups, and a nitrogen-containing ring compound (also called a 'base'). There are two classes of base, purines (which include the bases adenine and guanine) and pyrimidines (which include the bases thymine, cytosine, and uracil).

In this visual guide, you'll find the structures of thymine, cytosine, uracil, adenine, and guanine.

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