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Period: to
The Foundation of DNA
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P.A. Levene
Determined the basic structure of nucleotides that make up DNA. Nucleotides are subunits of nucleic acids and consist of a 5-carbon sugar, a phosphate group, and a nitrogenous base. Source: Online Textbook -
FGI, not RGIII
Fredrick Griffith experimented with streptococcus pneumoniae, he studied two strains of this, one sugar-coated and one not. He tested and found out theat the coated strain killed the mouse, even when mixed with the non-coated strain, which did not kill the mouse. This sparked the search for what transferred the "transforming substance". Source: Online Textbook -
Oswald Avery
Oswald Avery discovered that DNA was released when the S cells were killed, and some of the bacteria brought the DNA into their cells, changing the bacteria into S cells. Fact Source: Online Textbook -
Erwin Chargaff
Analyzed the amount of adenine, guanine, thymine, and cytosine in the DNA of various species.
Some of his data was published in 1950.
(Chargaff's rule: C=G and T=A) Source: Online Textbook -
Rosalind Franklin
Took famous photo 51, which showed DNA was a double-helix, a twisted ladder shape, formed by two strands of nucleotides twisted around each other. Source: Online Textbook -
Maurice Wilkins
A British physicist, and one of four scientists to join the search for DNA structure, and provide vital information for finding the correct structure of DNA. (along with Franklin, Crick, and Watson.) Source: Online Textbook -
Hershey and Chase
Alfred Hershey and Martha Chase proved that DNA was the "transforming factor" in Fredrick Griffith's experiment by knowing the bacteriophage used in the experiment was made of DNA and protein and that viruses can't replicate themselves. they then labeled both parts of the virus, and depicted which part was injected into the bacteria and which was the genetic material. Source: Online Textbook Source: Online Textbook Source: Online Textbook -
Linus Pauling
Proposed triple-stranded helix structure for DNA. But, he soon figured out that, the way he was constructing/designing it, the molecule would not hold together. So, the man who wrote the book on the chemical bond was incorrect. Source: DNA Interactive -
Watson and Crick
Using Chargaff's and Franklin's data, Watson and Crick created a model of the double helix of DNA. In 1953, published one-page letter in journal "Nature" that suggested DNA struct. and hyp. rep. method for mlc. dcd. fro. structure.- two outside strands consist of alternating deoxyribose and phosphate.
- cytosine and guanine bases pair to each other by three hydrogen bonds.
- thymine and adenine bases pair to each other by two hydrogen bonds.
