Double helix

Definition

The double helix is the structural formation of DNA, consisting of two intertwined strands that resemble a twisted ladder. This unique structure is crucial for the stability and functionality of DNA, allowing it to store genetic information efficiently while providing the mechanism for replication and transcription.

5 Must Know Facts For Your Next Test

1. The double helix structure was first described by James Watson and Francis Crick in 1953, based on data from Rosalind Franklin's X-ray diffraction images.
2. The twisting shape of the double helix helps protect the genetic code from damage and allows for efficient packaging of DNA within cells.
3. Each complete turn of the double helix contains about ten base pairs, contributing to its uniform width and overall stability.
4. The two strands of the double helix are held together by hydrogen bonds between the paired bases, which can easily break during processes like DNA replication.
5. The double helix structure allows for complementary base pairing, which is essential for accurate DNA replication and transcription into RNA.

Review Questions

• How does the double helix structure contribute to the stability and function of DNA?
  • The double helix structure provides stability to DNA due to its tightly coiled formation, which protects the genetic information inside. The hydrogen bonds between complementary bases also help maintain this structure while allowing flexibility during replication and transcription. This stability is essential for preserving genetic integrity over generations.
• Discuss how the concept of base pairing is vital for the processes of DNA replication and transcription.
  • Base pairing is critical during DNA replication as it ensures that each new strand is complementary to the original template strand. This specificity prevents errors in genetic information transfer. During transcription, base pairing facilitates the accurate synthesis of RNA from a DNA template, maintaining fidelity in gene expression.
• Evaluate the significance of Watson and Crick's model of the double helix in understanding modern genetics and molecular biology.
  • Watson and Crick's model of the double helix revolutionized our understanding of genetics by providing a clear framework for how genetic information is stored and transmitted. Their work laid the foundation for molecular biology techniques such as PCR and genome sequencing, influencing fields like genetic engineering and biotechnology. This model also highlighted the importance of complementary base pairing, leading to further insights into gene regulation and expression.

Related terms

Nucleotides: The building blocks of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Base pairing: The specific hydrogen bonding between nitrogenous bases in DNA, where adenine pairs with thymine and guanine pairs with cytosine.

Antiparallel strands: The orientation of the two strands in a double helix, where one strand runs in the 5' to 3' direction and the other runs in the 3' to 5' direction.