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

Nelson Bio 12
Ch. 4 – DNA : The Molecular Basis of Life
The History of DNA
The History of DNA
1869Freidrich Miescher
(Swiss)
 He first isolated the
material in the nucleus that
had an acid nature
 He called it nucleic acid
Meischer
PA Levene
1920’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.
1928 Frederick Griffith
 Trying to find a vaccine for
pneumonia. Griffith found
“something” transformed
the harmless bacteria into
the harmful bacteria
 Do Lab exercise 4.1.1 on
pg.226.
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).
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)
1953 : James Watson & Francis Crick
Won the race to determine the double helix
arrangement of DNA (Cambridge, England)
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.
Rosalind Franklin
1961:
Francis Crick and coworkers discover the triplet
codon which codes for amino acids during protein
synthesis