Download ANSWERS- The History of DNA

ANSWERS- The History of DNA
1869 - Friedrich Miescher(Swiss) -first isolated the material in the nucleus that had an
acid nature. He called it nucleic acid.
1920's – P.A. Levene - determined that nucleic acid contained a deoxyribose sugar, a
phosphate group, and 4 nitrogenous bases. He didn’t know the exact molecular
arrangement, but he did know that one sugar, one phosphate and one nitrogenous base
linked together to form a unit (he called this unit a nucleotide). Since there are four
different bases, there are four different DNA nucleotides.
1928 - Frederick Griffith – when trying to find a vaccine for pneumonia, Griffith found
that “something” transformed the harmless bacteria into the harmful bacteria.
1944 - Avery, MacLeod, McCarty - identified the transforming material in Griffith’s
experiment as DNA.
1951- Erwin Chargaff - determined that the amount of adenine equalled the
amount of thymine and the amount of guanine equalled the amount of cytosine.
This is known as the « Rule of Chargaff »
1952 - Al Hershey & Martha Chase - used viruses which attack bacteria (bacteriophages)
to show that it’s only the DNA from the phage which enters the bacteria and takes
control, not the entire phage.
1953 - James Watson and Francis Crick - determined the double helix arrangement of
DNA (Cambridge, England)
** Note: In early 1953, Maurice Wilkins and Rosalind Franklin (both radiologists) gave
Watson & Crick the most important information that helped them solve the DNA riddle ->
X-ray data that showed the repeating units of DNA formed a helix.
Rosalind Franklin died of cancer due to exposure to too much radiation in her work.
Shortly after her death (in 1962) Watson, Crick and Wilkins received the Nobel Prize and
Franklin was given
no credit.
1961 - Francis
discovered the
for an amino acid
Crick & coworkers triplet codon that codes
during protein synthesis.