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Unformatted text preview: id chemical analysis 9 Finding the “transforming principle”
1944 Avery, MacLeod and McCarty
Prepared various purified and semi-purified components
from the mixture and tested to see if they could transform
R form bacteria. The only one that could was determined
to be DNA.
Further tested this preparation by subjecting it to
various chemicals………. They suggested genes were made up of DNA
10 Avery’s demonstration of in vitro transformation 11 More evidence that genes are made
of DNA 1952 – Experiments of Chase and Hershey,
infecting bacterial cells with bacteriophages
looked at viruses instead of cells 12 Evidence that genes are made of DNA
T2 bacteriophages are very small, and are
composed of approximately equal weights
of protein and DNA. They depend on
the host cell machinery for their replication.
What substance directs the production of
new phage particles, DNA
or protein ?
13 Evidence that genes are made of DNA 14 attachment / injection Electron microscope revealed that when phage infect
bacteria, they leave the viral shell (ghost) on the surface of
the cell. It appeared that the substance for phage replication was
injected into the cell.
Hershey and Chase set about showing which substance
was DNA and which was protein. 16 The chemical constituents of DNA
The parts: 17 The chemical constituents of DNA
Assembly into a nucleotide : 18 The chemical constituents of DNA Nucleotides linked in a
directional chain through
5’ phosphate and 3’ hydrox...
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