1. Nelson Bio 12 Ch. 4 – DNA : The Molecular Basis of Life
The History of DNA

2. The History of DNA
Freidrich Miescher (Swiss)
Meischer
He first isolated the material in the nucleus that had an acid nature
He called it nucleic acid

3. PA Levene ’s
Levene determined that nucleic acid contained deoxyribose sugar, a phosphate group and 4 nitrogenous bases
He didn’t know the molecular arrangement but he did know that the one sugar, one phosphate and one base linked together
He called this unit a nucleotide.

4. 1928 Frederick Griffith
Trying to find a vaccine for pneumonia. Griffith found “something” transformed the harmless bacteria into the harmful bacteria
Do Lab exercise on pg.226.

5. 1944: Oswald Avery, Colin MacLeod,Maclyn McCarty
They identified the transforming material in Griffith’s experiment as DNA
( review your lab exercise from pg. 226).

6. 1952: Al Hershey & Martha Chase
They used viruses which attack bacteria (phages) to show that it’s the DNA from the virus which enters the bacteria and takes control
(the protein coats remain outside the host and it’s only DNA injected inside)

7. 1953 : James Watson & Francis Crick
Won the race to determine the double helix arrangement of DNA (Cambridge, England)

8. Rosalind Franklin , Maurice Wilkins
Both were radiologists who gave Watson and Crick the most important information to help them solve the DNA riddle
It was x-ray data 1953.
Famous and known as photo 51.
Rosalind Franklin died of cancer due to exposure to too much radiation in her work. Shortly after in 1962 Watson & Crick received the Nobel Prize and Franklin was given no credit.

9. Rosalind Franklin

10. 1961:
Francis Crick and coworkers discover the triplet codon which codes for amino acids during protein synthesis