Nitrogenous base

Definition

A nitrogenous base is a molecular component of nucleotides, which are the building blocks of DNA and RNA. These bases contain nitrogen and are essential for the storage and transmission of genetic information. In DNA, nitrogenous bases pair with each other to form the rungs of the double helix structure, connecting the two strands of the DNA molecule.

5 Must Know Facts For Your Next Test

1. There are four main nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G).
2. Nitrogenous bases are divided into two categories: purines (adenine and guanine) and pyrimidines (cytosine and thymine).
3. The order of nitrogenous bases in a DNA molecule encodes genetic information, determining traits and functions in living organisms.
4. In RNA, the nitrogenous base uracil (U) replaces thymine (T), pairing with adenine instead.
5. The stability of the DNA double helix is partly due to hydrogen bonds formed between complementary nitrogenous bases.

Review Questions

• How do nitrogenous bases contribute to the structure of DNA?
  • Nitrogenous bases are crucial for the structure of DNA as they form the rungs of the double helix ladder. They pair specifically through complementary base pairing, where adenine pairs with thymine and cytosine pairs with guanine. This pairing not only stabilizes the DNA structure but also allows for accurate replication during cell division, ensuring genetic information is correctly passed on.
• Compare the roles of nitrogenous bases in DNA versus RNA.
  • In DNA, nitrogenous bases play a critical role in encoding genetic information through their specific sequences, while also forming stable base pairs that hold the double helix structure together. In contrast, RNA uses nitrogenous bases to help translate that genetic information into proteins. Notably, RNA replaces thymine with uracil, altering its base pairing dynamics but still maintaining functionality in protein synthesis.
• Evaluate the significance of complementary base pairing among nitrogenous bases in terms of genetic fidelity.
  • Complementary base pairing among nitrogenous bases is essential for maintaining genetic fidelity because it ensures accurate replication of DNA during cell division. The specific pairing mechanism minimizes errors when DNA is copied, as only correctly matched bases can bond effectively. This high level of specificity allows for consistent transmission of genetic information across generations, reducing mutations that could lead to diseases or developmental issues.

Related terms

nucleotide: The basic structural unit of DNA and RNA, composed of a sugar, a phosphate group, and a nitrogenous base.

complementary base pairing: The specific pairing of nitrogenous bases in DNA; adenine pairs with thymine, and cytosine pairs with guanine.

adenine: One of the four primary nitrogenous bases in DNA and RNA, which pairs with thymine in DNA and uracil in RNA.