Complementary base pairing

Definition

Complementary base pairing is the specific hydrogen bonding between nitrogenous bases in DNA and RNA, where adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine. This pairing is fundamental for the stability of the nucleic acid structure and is crucial for processes like DNA replication and transcription, ensuring accurate genetic information transfer.

5 Must Know Facts For Your Next Test

1. Complementary base pairing is essential for the formation of the double helix structure of DNA, allowing it to maintain its integrity during replication.
2. Adenine and thymine are held together by two hydrogen bonds, while cytosine and guanine are connected by three hydrogen bonds, affecting their stability and strength.
3. This base pairing mechanism ensures fidelity in DNA replication, reducing errors that could lead to mutations.
4. In RNA, uracil replaces thymine and pairs with adenine, showing that complementary base pairing is also crucial for RNA structure and function.
5. Complementary base pairing plays a key role in the processes of transcription and translation, as it dictates how RNA interacts with DNA and ribosomes.

Review Questions

• How does complementary base pairing contribute to the stability of the DNA double helix?
  • Complementary base pairing contributes to the stability of the DNA double helix by forming specific hydrogen bonds between paired bases. Adenine pairs with thymine through two hydrogen bonds, while cytosine pairs with guanine through three hydrogen bonds. This specific pairing not only maintains the helical structure but also ensures that each strand can serve as a template for replication, thereby preserving genetic information.
• Discuss the role of complementary base pairing in DNA replication and how it helps prevent mutations.
  • During DNA replication, complementary base pairing ensures that each original strand serves as a template for a new strand. DNA polymerase synthesizes new strands by adding nucleotides that are complementary to the template strand. This specificity minimizes errors because incorrect pairings are less stable and can lead to failed bonding. Therefore, accurate complementary base pairing is critical in reducing mutation rates during cell division.
• Evaluate how complementary base pairing differs between DNA and RNA and the implications this has for their respective functions.
  • Complementary base pairing differs between DNA and RNA primarily in one base: thymine is found in DNA, while uracil is present in RNA. This distinction impacts their stability; RNA is generally more prone to degradation due to its single-stranded nature compared to the stable double helix of DNA. These differences are significant because they dictate how each molecule functions in biological processes—DNA serves as long-term genetic storage, while RNA plays a dynamic role in protein synthesis and regulation.

Related terms

DNA:

Deoxyribonucleic acid, the molecule that carries genetic instructions for the development and functioning of living organisms.

RNA:

Ribonucleic acid, a molecule that plays a central role in the synthesis of proteins and can also have regulatory functions within cells.

Hydrogen bond: A weak bond that occurs when a hydrogen atom covalently bonded to an electronegative atom is attracted to another electronegative atom, crucial for the stability of the double helix structure in nucleic acids.