DNA Molecular Structure Quiz

Study Notes

Rosalind Franklin, Gosling, and Maurice Wilkins identified DNA's helical structure, positioning of sugars and phosphates on the exterior, with nucleotides situated inside.
James Watson and Francis Crick proposed a triple-helix model but later corrected their model to a double helix with complementary base pairing.
Linus Pauling suggested a triple helix model but was later outweighed by Watson and Crick's findings.

John Griffith established that nucleotides stack flatly; noted adenine pairs with thymine and cytosine pairs with guanine, crucial for DNA replication.
Erwin Chargaff observed a consistent purine-pyrimidine ratio (1:1) which became known as Chargaff's rule.
Jerry Donohue discovered that hydrogen positions in nitrogenous bases can shift, affecting hydrogen bonding.

"Molecular Structure of Nucleic Acid" published in April 1953 in Nature (Volume 171: 737-738).
"Genetic Implications of the Structure of Deoxyribonucleic Acid" published in May 1953 in Nature (Volume 171: 964-967).

James Watson, Francis Crick, and Maurice Wilkins received the Nobel Prize in 1962 for their work on DNA's structure, with Rosalind Franklin omitted due to her passing in 1958.

1830: Proteins were deemed the most crucial biological molecules.
Late 1860s: Friedrich Miescher isolated a distinct molecule from the nucleus (DNA); salmon sperm DNA’s empirical formula identified as $C_{29}H_{49}N_9P_3O_{22}$.
1866: Ernst Haeckel recognized the nucleus as a major cellular component, while Edmund Wilson concluded DNA was the primary nuclear element passed through generations.
1928: Frederick Griffith demonstrated the "transforming principle" using Streptococcus pneumoniae to prove the existence of genetic material.
1944: Oswald Avery, Colin Macleod, and Maclyn McCarty determined that the transforming principle was DNA through experiments involving degradation by proteins and RNAs versus DNAs.
1952: Alfred Hershey and Martha Chase confirmed that DNA is the genetic material of viruses through their blender experiment, distinguishing DNA from protein components.
1952: Norton Zinder, Joshua, and Esther Lederberg reinforced that DNA acts as genetic material via transduction experiments in Salmonella typhimurium.
1953: Formation of the DNA double helix model attributed to Franklin, Wilkins, Watson, and Crick.

Francis Crick earned a Ph.D. in biophysics, starting protein x-ray studies in 1947 at Cambridge.
James Watson attained a Ph.D. in microbiology from the University of Indiana, transferring to Cambridge in 1951.
Maurice Wilkins, with a Ph.D. in physics, contributed to radar and the Manhattan Project, serving as assistant director of medical research at King's College London.