Base Pairing Rule

Definition

The base pairing rule refers to the specific pairing of nitrogenous bases in DNA, where adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). This rule is crucial for the structure of DNA, as it ensures that the double helix is formed correctly and maintains its stability during processes like replication and transcription. The accuracy of this pairing is essential for genetic fidelity and plays a significant role in the overall functioning of living organisms.

5 Must Know Facts For Your Next Test

1. The base pairing rule is fundamental to the structure of the DNA double helix, allowing it to maintain a uniform width.
2. Adenine and thymine form two hydrogen bonds, while cytosine and guanine form three hydrogen bonds, affecting the stability of DNA.
3. Errors in base pairing can lead to mutations, which can have significant effects on an organism's traits and functions.
4. During DNA replication, each original strand serves as a template for creating a new complementary strand based on the base pairing rule.
5. The base pairing rule also applies to RNA synthesis during transcription, where adenine pairs with uracil instead of thymine.

Review Questions

• How does the base pairing rule contribute to the stability of the DNA double helix structure?
  • The base pairing rule contributes to the stability of the DNA double helix structure by ensuring that adenine pairs with thymine and cytosine pairs with guanine. This specific pairing allows for consistent spacing between the two strands, maintaining a uniform width throughout the helix. The hydrogen bonds formed between these complementary bases help hold the strands together, providing structural integrity that is essential for DNA's function in heredity.
• Discuss the implications of errors in base pairing during DNA replication and how they can affect genetic information.
  • Errors in base pairing during DNA replication can lead to mutations, which are changes in the genetic sequence. If a base is incorrectly paired, it can result in the incorporation of an incorrect nucleotide into the new strand, potentially altering gene function or expression. Such mutations can have various effects, ranging from benign variations to serious conditions or diseases, highlighting the importance of accurate base pairing for maintaining genetic integrity.
• Evaluate the role of the base pairing rule in both DNA replication and transcription, and discuss its significance in gene expression.
  • The base pairing rule plays a critical role in both DNA replication and transcription by ensuring that genetic information is accurately copied and expressed. During replication, each original strand serves as a template for synthesizing a complementary strand through specific base pairings. In transcription, this rule allows for the synthesis of RNA from DNA, where adenine pairs with uracil instead of thymine. This accuracy is vital for proper gene expression and protein synthesis, ultimately influencing an organism's traits and functions.

Related terms

DNA Replication: The process by which a cell makes an exact copy of its DNA, ensuring that genetic information is passed on during cell division.

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

Complementary Strands: Strands of DNA that run in opposite directions and are held together by hydrogen bonds between their complementary bases, following the base pairing rule.