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Discovery of nucleic acids
Friederich Miescher isolated the genetic material from white blood cell nuclei. He named it nuclein. -
Discovery of DNA components
Phoebus Levene Discovered the components of DNA, these being: adenine, guanine, thymine, cytosine and deoxyribose phosphate.
He defined phosphate-sugar-base units called nucleotides. -
Levene's Tetranucleotide
Levene thought that there were four nucleotides per molecule. Levene thought that phosphoester was the one to bound the nucleotides. -
Friederich Griffith and his transformation experiment
He studied the epidemiology and pathology of 2 strains of streptococco and he observed the first widely accepted demonstrations of bacterial transformation. -
Avery, MacLeod and McCarty ( cause of the transformation )
Determined the cause of the transformation in Griffith's Experiment
They took live R and heat-treated S and mixed it with one of two enzymes:
a protease (destroys protein)
a DNAse (destroys DNA) -
Watson and Crick Inside-Out Double Helix
Watson and Crick wrote a paper in which they described DNA as a double helix with sugars and phosphates at the center and the nucleobases facing the outside
This model was quickly shown to be incorrect and in fact it made no chemical sense -
Chargaff's rules
Erwin Chargaff used paper chromatography and UV spectroscopy to count the nucleobases and studied the percentages of Adenine, Thymine, Cytosine and Guanine that there were.He noticed a very strange thing that was named the Chargaff rules. Chargaff's rules stated that the amount of Adenine was equal to the amount of Thymine and that the amount of Cytosine was equal to the amount of Guanine. These rules apply to all species, with no exceptions. -
Hershey-Chase Experiments
The Hershey-Chase experiments concluded that DNA, was the genetic material, and not protein. -
Photo 51
Rosalind Franklin takes a picture that shows clearly that the structure of DNA is a double Helix.The photo is stolen by Maurice Wilkins and delivered to Crick and Watson. -
Pauling's triple helix
Linus Pauling and Robert Corey presented the triple helix as the structure of the DNA, but they were incorrect. -
Watson and Crick correct double helix
After seeing Photo 51, Watson and Crick realise their previous model was inside out.
They built the model based on Rosalind's photo and finally confirmed that that was the structure of DNA. -
The nobel prize in physiology or medicine
Francis Crick, James Watson and Maurice Wilkins ended up winning the Nobel prize for their discoveries, but Rosalind died from Ovarian cancer due to the exposure to the X rays and wasn't given the prize, since Nobel prizes are only awarded to living persons.
Sadly none of them acknowledged the importance of her work in their discovery and they were the ones that got famous and got all the credit.