Download Road To Discovery of DNA

Road To Discovery of DNA
Timeline to DNA
• Mendel (1865) – performed and recorded
crosses with pea plants to study aspects of
heredity.
• Sutton & Boveri (1902) – identified
similarities between Mendel’s factors and the
behavior of chromosomes.
Levene
• Phoebus Levene (1900’s) – made important
observations of the structures of nucleic acids.
– 2 different sugar groups – Ribose or Deoxyribose
– contain repeating subunits he called nucleotides
– both DNA/RNA contain 1 of 4 different nitrogen
bases. (A, C, G and T or U).
Transformation
• Fred Griffith (1928) – discovered the
transforming principle while working with
pathogenic bacteria.
• MacLeod, McCarty & Avery (1940’s) – used
live/dead bacteria to carry out experiments to
verify the work by Griffith describing how the
transformation principle worked.
Transforming Principal
Base Pairing Rule!!
• Erwin Chargaff (1940’s - 50’s) – Chargaff
overturned the theory of Levene’s base pairing
conclusions and discovered that amount of:
– Adenine = Thymine and Cytosine = Guanine
• CHARGFF’S RULE - A=T and C=G.
Final Proof for DNA as the agent of
heredity
• Alfred Hershey & Martha
Chase (1952) – using
radioactive labelling
techniques proved that it
was Nucleic Acid NOT
Proteins that caused the
transmission of genetic
information to future
generations of viruses.
DNA Structure
• Franklin’s and Wilkins (1950) – used x-ray
diffraction analysis of a DNA molecule to
decipher special repeating patterns in the
physical makeup of the molecule.
• Watson and Crick (1953) – used the work of
Wilkins to be the first to publish the complete
structure of the DNA molecule.
Watson and Crick – Nobel Prize
Winners
• 1957 – Barbara McClintock –
– Transposons (jumping genes) – these are
short sections of DNA that can move from
one location to another within a cell’s
genetic make-up.
– These modifications to the genetic code can
effect the final gene products produced.
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