Final answer:
Watson and Crick used X-ray diffraction data, notably from Rosalind Franklin, and combined it with Chargaff's rules to develop their double helix model of DNA, without conducting their own experiments.
Step-by-step explanation:
Discovery of the DNA Structure
In the 1950s, Francis Crick and James Watson utilized X-ray diffraction data from Rosalind Franklin to piece together the double helix structure of DNA. Unlike earlier experimenters who conducted controlled experiments like Griffith, Avery, and Hershey and Chase, Watson and Crick did not perform their own experiments but instead built upon existing research and information.
Franklin had shown through her X-ray diffraction images the helical nature of DNA, which Watson and Crick interpreted to model the double-stranded structure. Their use of Chargaff's rules, which indicated that certain DNA nucleotides always appeared in equal proportions, further guided them to propose the pairing now known as base pairing.
Rosalind Franklin's work was critical but often under recognized, whereas Watson and Crick's fame largely comes from the publication of the DNA model in their original Nature article. This model provided the foundation for understanding how DNA encodes information and how it is replicated, which underpins all modern biotechnologies.
One such technology is the polymerase chain reaction (PCR), a technique for amplifying DNA sequences. PCR and other biotechnological innovations like gene sequencing, DNA fingerprinting, and genetically modified foods rely on the fundamental understanding of DNA structure and function that Watson and Crick's model provided.