Explain how the biochemical characterisation (nature) of ‘Transoforming Principle’ was determined. which was not defined from Griffith’s experiments.

Solution

Transforming Principle :

In 1928, Frederick Griffith, in a series of experiments with Streptococcus pneumoniae (bacterium responsible for pneumonia), witnessed a miraculous transformation in the bacteria. During the cource of his experiment, a living organism (bacteria) had changed in physical form.

He concluded that the R strain bacteria had somehow been transformed by the heat - killed S strain bacteria. Some ‘transforming principle’, transferred from the heat-killed S strain, had enabled the R strain to synthesise a smooth polysaccharide coat and become virulent. This must be due to the transfer of the genetic material. However, the biochemical nature of the genetic material was not defined from his experiments.

Oswald Avery, Colin MacLeod and Maclyn McCarty worked to determine the biochemical nature of ‘tranforming principle’ in Griffith’s experiment.

They purified biochemicals (proteins, DNA, RNA, etc.) from the heat-killed S cells to see which ones could transform live R cells into S cells. They discovered that DNA alone from S bacteria caused R bacteria to become transformed.

They also discovered that protein - digesting enzymes (proteases) and RNA - digesting enzymes (RNases) did not affect transformation, so the transforming substance was not a protein or RNA. Digestion with DNase did inhibit transformation, suggesting that the DNA caused the transformation.
They concluded that DNA is the hereditary material, but not all biologist were convinced.

Some More Questions From Molecular Basis of Inheritance Chapter

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Molecular Basis Of Inheritance

Explain how the biochemical characterisation (nature) of ‘Transoforming Principle’ was determined. which was not defined from Griffith’s experiments.

Some More Questions From Molecular Basis of Inheritance Chapter

What made DNA more preferrable as genetic material ?

Process of replication is completed in how much time in E.coli ?

What is average rate of polymerization ?

List three components of transcription unit.

Which RNA acts as an adapter ?

Name three kinds of polymerases.

What is splicing ?

Which is more stable DNA or RNA?

Expand UTR.

Where are UTRs present in mRNA strand ?

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