The Open Door Web Site
Molecular Genetics Index
The Nucleic Acids
The Chemical Nature of the Gene
The molecules which are genes must have two properties:
Whatever genes are made of it must be a big molecule to hold the large amount of information required to build an organism.
It must be a complex molecule to provide the necessary variation to code the instructions which control growth and development.
Griffiths' Experiment (1928)
Transformation of R-type to S-type
Avery, MacCleod & McCarthy (1944)
Tried purifying the transforming principle to change R-type Pneumococcus to S-type.
The compound that had the most effect was:
The transforming principle is a nucleic acid
DNA is the transforming principle and it it is hereditary material.
The DNA was not totally pure, it was contaminated by a small amount of protein. This protein could be the real transforming principle.
When Avery and his team prepared purer extracts of DNA they became better at transforming the bacteria types.
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