Double helix

Definition

The double helix is the structure of DNA, consisting of two long strands that twist around each other, resembling a spiral staircase. This shape is crucial because it allows for the storage and replication of genetic information, with the sequence of nucleotide bases on each strand pairing specifically to encode the instructions for building proteins and maintaining life.

5 Must Know Facts For Your Next Test

1. The double helix was first described by James Watson and Francis Crick in 1953, based on X-ray diffraction images produced by Rosalind Franklin.
2. Each strand of the double helix runs in opposite directions, known as antiparallel orientation, which is important for replication and enzyme activity.
3. The hydrogen bonds between the complementary bases hold the two strands together, providing stability to the double helix structure.
4. The sequence of bases along the DNA strands encodes genetic information, which is read in sets of three called codons during protein synthesis.
5. The discovery of the double helix structure has been fundamental to the field of genetics and molecular biology, influencing research in heredity, evolution, and biotechnology.

Review Questions

• How does the structure of the double helix facilitate the processes of DNA replication and protein synthesis?
  • The double helix structure allows for complementary base pairing between nucleotides on opposite strands, which is essential during DNA replication. As the double helix unwinds, each strand serves as a template for creating a new complementary strand. This ensures that genetic information is accurately copied. Additionally, during protein synthesis, the sequence of bases on the DNA is transcribed into mRNA, which then translates into proteins, highlighting how the structure supports both replication and gene expression.
• Evaluate the significance of Rosalind Franklin's contributions to our understanding of the double helix structure of DNA.
  • Rosalind Franklin's X-ray diffraction images provided critical evidence for determining the double helix structure of DNA. Her famous Photo 51 revealed the helical shape and dimensions of DNA, which were essential for Watson and Crick to develop their model. Despite her vital contributions being overlooked initially, Franklin's work emphasizes the importance of collaboration and recognition in scientific discoveries, influencing how we understand molecular biology today.
• Synthesize information from various sources to explain how the discovery of the double helix has impacted advancements in genetics and biotechnology.
  • The discovery of the double helix has fundamentally transformed our understanding of genetics and biotechnology. It paved the way for molecular cloning techniques and genetic engineering, allowing scientists to manipulate DNA sequences for various applications such as gene therapy, agricultural improvements, and forensic analysis. Furthermore, this discovery has led to significant advances in fields like genomics and personalized medicine, enabling targeted treatments based on individual genetic profiles. The implications continue to resonate across multiple disciplines, showcasing how a single structural insight can catalyze widespread scientific innovation.

Related terms

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

Complementary Base Pairing: The specific pairing of nitrogenous bases in DNA, where adenine pairs with thymine and guanine pairs with cytosine.

Replication: The process by which DNA makes a copy of itself before cell division, ensuring that each new cell receives an identical set of genetic information.