Complementary base pairing

Definition

Complementary base pairing is the specific hydrogen bonding between nucleotide bases in DNA and RNA, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine. This pairing is crucial for maintaining the double helical structure of DNA, ensuring accurate replication, and facilitating the process of transcription. By forming stable bonds between complementary bases, this mechanism supports genetic fidelity and proper gene expression.

5 Must Know Facts For Your Next Test

1. Complementary base pairing is essential for the double helix structure of DNA, as it stabilizes the molecule through hydrogen bonds.
2. Adenine (A) and thymine (T) form two hydrogen bonds, while cytosine (C) and guanine (G) form three hydrogen bonds, influencing the stability of DNA.
3. During DNA replication, complementary base pairing ensures that the genetic information is accurately copied, allowing for genetic continuity.
4. In RNA, uracil (U) replaces thymine (T), so adenine pairs with uracil in RNA molecules during processes like transcription.
5. Errors in complementary base pairing can lead to mutations, which may affect protein synthesis and overall cellular function.

Review Questions

• How does complementary base pairing contribute to the structure of DNA?
  • Complementary base pairing is fundamental to the structure of DNA because it allows for the specific pairing of nitrogenous bases, which stabilizes the double helical structure. Adenine pairs with thymine, and cytosine pairs with guanine through hydrogen bonds, creating the rungs of the DNA ladder. This specificity ensures that the DNA maintains its structure and function as a carrier of genetic information.
• Discuss the role of complementary base pairing in the accuracy of DNA replication.
  • Complementary base pairing plays a crucial role in ensuring the accuracy of DNA replication by allowing DNA polymerase to correctly match new nucleotides to their corresponding bases on the template strand. This matching process minimizes errors during replication, as only complementary bases can form stable hydrogen bonds. The high fidelity of this pairing is essential for preserving genetic information across generations.
• Evaluate the implications of errors in complementary base pairing on genetic processes such as transcription and translation.
  • Errors in complementary base pairing can have significant implications for genetic processes like transcription and translation. For instance, if a mistake occurs during transcription due to incorrect base pairing, it can lead to the synthesis of faulty mRNA, which might produce nonfunctional or harmful proteins. This disruption can affect cellular functions and contribute to diseases. Understanding how complementary base pairing works helps us grasp why precision is vital in maintaining genetic integrity and proper cellular behavior.

Related terms

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

DNA Polymerase: An enzyme responsible for synthesizing new DNA strands by adding nucleotides to a growing chain during DNA replication.

Transcription: The process by which the information in a gene's DNA is copied into messenger RNA (mRNA), which then guides protein synthesis.