🦠microbiology review

Nitrogenous bases

Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025

Definition

Nitrogenous bases are organic molecules that contain nitrogen and act as the fundamental building blocks of nucleic acids like DNA and RNA. They pair with each other to form the rungs of the DNA double helix, enabling genetic information storage and transfer.

AP course connection

Topic 10.2: 10.2 Structure and Function of DNA

Unit 10

5 Must Know Facts For Your Next Test

  1. There are five primary nitrogenous bases: adenine (A), thymine (T), cytosine (C), guanine (G), and uracil (U).
  2. In DNA, adenine pairs with thymine, and cytosine pairs with guanine through hydrogen bonds.
  3. Uracil replaces thymine in RNA, pairing with adenine instead.
  4. Nitrogenous bases are classified into two categories: purines (adenine and guanine) and pyrimidines (cytosine, thymine, and uracil).
  5. The sequence of nitrogenous bases in DNA determines an organism's genetic code.

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