Base pairing

Definition

Base pairing refers to the specific hydrogen bonding between nitrogenous bases in nucleic acids, which is fundamental for the structure of DNA and RNA. This pairing occurs through complementary interactions, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine, allowing for the stable formation of the double helix structure in DNA and the single-stranded structure in RNA. These interactions are crucial for processes such as DNA replication and transcription, ensuring accurate genetic information transfer.

5 Must Know Facts For Your Next Test

1. Base pairing is essential for maintaining the helical structure of DNA, as it stabilizes the two strands through hydrogen bonds.
2. Adenine (A) forms two hydrogen bonds with thymine (T) in DNA and uracil (U) in RNA, while cytosine (C) forms three hydrogen bonds with guanine (G).
3. The specificity of base pairing ensures fidelity during DNA replication, reducing the chances of mutations.
4. In addition to DNA, base pairing also plays a role in the structure of RNA, particularly in tRNA and rRNA molecules.
5. Base pairing allows for the formation of secondary structures in RNA, such as hairpins and loops, which are important for its function.

Review Questions

• How does base pairing contribute to the stability and structure of DNA?
  • Base pairing is fundamental to the stability and structure of DNA as it involves specific hydrogen bonds between complementary bases: adenine pairs with thymine, and cytosine pairs with guanine. These interactions not only hold the two strands of the double helix together but also contribute to its overall stability. The precise pairing ensures that the genetic code can be accurately preserved and transmitted during processes like replication.
• Discuss the implications of base pairing errors during DNA replication.
  • Errors in base pairing during DNA replication can lead to mutations, which may alter gene function and contribute to various diseases. For instance, if adenine mistakenly pairs with cytosine instead of thymine, this can result in a mismatch that may not be corrected by DNA repair mechanisms. Such mutations can have significant impacts on protein synthesis, leading to dysfunctional proteins or changes in cellular behavior that may promote conditions like cancer.
• Evaluate the role of base pairing in RNA functions beyond its role in DNA transcription.
  • Base pairing plays a critical role in various RNA functions beyond transcription from DNA. In tRNA, for example, base pairing is essential for its ability to accurately match amino acids with their corresponding codons during translation. Similarly, base pairing is vital in forming secondary structures within rRNA that are crucial for ribosome function. Furthermore, in regulatory RNAs like miRNA and siRNA, base pairing facilitates their interaction with target mRNAs, influencing gene expression post-transcriptionally.

Related terms

Nucleotide: The basic building block of nucleic acids, composed of a sugar, a phosphate group, and a nitrogenous base.

Hydrogen Bond: A weak bond that occurs between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom, crucial in stabilizing the DNA structure.

Complementary Base Pairing: The specific pairing of nitrogenous bases (A-T and C-G) that ensures the accurate replication and transcription of genetic information.