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Discobery of Nucleic Acids
It was discovered by Friedrich Miescher that was a Swiss physical and biologist. He was born in 1844 in swidden, and he died in 1895 also in swidden. He studied in the Basilea University. Also, he isolated the genetic material that come from the white blood cell nuclei in 1869. Furthermore, he noted it had an acidic nature, and he called it nuclein and with this he prepared the way to identify them as the bearing from the DNA. -
Leven's Tetranucleotide
Levene proposed that there were four nucleotides per molecule. Also, he proposed that DNA could not store the genetic code because chemically far too simple. -
Discobery of DNA components
It was discovered by Phoebus Levene that was a Lithuanian-American Biochemist, he was burned in 1869 in Lithuania and died in 1940 in New York. He studied in the Columbia University. He wins a Willard Gibbs price in 1931. Furthermore, he determined the components of DNA that were: adenine, guanine, thymine, cytosine, deoxyribose phosphate. Also, he defined the phosphate-sugar-base units called nucleotides. -
Griffith's Transformation Experiment
It was made by Frederick Griffith was a doctor and also geneticist, he was born in 1877 in UK, and he died in 1941 also in the UK, he studied the epidemiology and pathology of 2 strains of Streptococcus pneumoniae. In 1928, he did his most famous experiment the Griffith's experiment, with this he proved that bacteria can transfer genetic information by a process called transformation. He observed bacterial transformation, but did not understand the mechanism it has. -
Griffith's experiment explanation.
Avery, MacLeod and McCarty discovered the explanation of Griffith's experiment. With their experiments in 1944 determined the cause of the transformation in Griffith's experiment. They took a live R and heat treated S and mixed it with one of two enzymes. They see that proteases which destroys protein and DNA which destroys DNA. These results were published in the Journal of Experimental Medicine. They said that DNA not protein was responsible for the bacterial transformation. -
The DNA was a double Helix?
In 1951, 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. -
Hershey-Chase Experiments
These experiments were made by Alfred Hershey,Martha Chase. Bacteriophage (phage) is a virus that infects bacteria. They are made of DNA and protein. They use a bacteria cell, and then they took the bacteriophage labelled in one or two ways, either with radioactive sulfur, and that allow them to follow the proteins in the phage, or they use radioactive DNA to follow the movement of DNA during the infection. With this, they conclude that DNA was the genetic material and not the protein. -
Counting Nucleobases
Erwin Chargaff, that was an Austrian biochemist, was counting Nucleobases in 1952.
Used paper chromatography and UV spectroscopy to examine the abundance of the nucleobases and he started to notice something VERY odd... This came to be known as "Chargoff's Rules" he noticed that the amounts of Adenine were the same amount as the amounts of Thymine and the Amounts of Cytosine were the same as the amounts of Guanine. This was the same in all the species in the world. -
Triple Helix?
Linus Pauling and Robert Corey proposed a triple Helix as the structure of the DNA. That also turned down to be incorrect. -
DNA with a Double Helix
Francis Crick, James Watson, Maurice Wilkins they were working at the Cavendish labs in Cambridge and Rosalind Franklin at King's collage in London. Rosalind took a lot of amazing photographs of the B form of DNA, she figures how to see the wet form that is the form that exist in cells. He took a photo that shows very clearly the X in the middle that is a sign of a double helix Rosalind was not prepared to publish this until she finishes all the calculations, -
DNA with a Double Helix
but Maurice Wilkins get the photo and manage to get it to Watson and creek in Cambridge, when they see the image they know exactly what it means their model from 1951 was backwards the model based on Rosalind's image, and also we have the paper that exactly describes how DNA looks like. So Watson and Crick Model was the correct one. So with this we know that DNA is a double-stranded Helix made of sugar and phosphate groups runing anti-parallel.