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Frederick Griffith was a British bacteriologist, physician and pathologist who performed transformation experiments that suggested that DNA was the hereditary material. His focus was on the epidemiology and pathology of bacterial pneumonia – which led him to develop the principle of bacterial transformation. The principle of bacterial transformation allowed scientist to transform a bacterium through the introduction of exogenous DNA carrying the gene of interest into the recipient organism or bacteria. His notable work ushered in the field of molecular microbiology because of his discovery of DNA as the main genetic material of the cell.


Frederick showed that Streptococcus pneumoniae could transform from one strain into a different strain, an effect he attributed to an unidentified transforming principle or factor. In 1928, Frederick reported what is now known as Griffith’s Experiment, which was the first widely accepted demonstration of bacterial transformation. Frederick’s student, Avery Oswald, later demonstrated this principle of bacterial transformation conclusively. Frederick Griffith’s work established the foundation of molecular genetics, a field which is thriving today in the biomedical, biological and medical sciences. His work showed that DNA is the genetic material of the cell. 

FRANCIS CRICK (1916-2004)

Francis Crick was an English molecular biologist, biophysicist, and neuroscientist who contributed to the discovery of the DNA as the genetic material of the cell. He co-discovered the molecular structure of the genetic material (DNA) with James Watson in 1953. Francis Crick showed in his work that genetic information flows from the DNA to RNA and then to protein; and he referred to this very important concept of molecular biology as the “central dogma” of molecular biology. Crick, James Watson and Maurice Wilkins (1916-2004) were jointly awarded the Nobel Prize on Physiology or Medicine in 1962 for their discovery of the molecular structure of the DNA.

Apart from his contribution in discovering the structure of nucleic acids (particularly the DNA), Crick will be famously remembered for coming up with the idea that the genetic information of an organism actually flow between informational macromolecules in certain direction: i.e., from DNA to RNA to Protein, and then to the traits expressed in the individual organism. His concept of the flow of informational (genetic) molecules explained the central dogma of molecular biology which was also opined by Fredrick Griffith, Avery and colleagues.   

Further reading

Brooks G.F., Butel J.S and Morse S.A (2004). Medical Microbiology, 23rd edition. McGraw Hill Publishers. USA. Pp. 248-260.

Madigan M.T., Martinko J.M., Dunlap P.V and Clark D.P (2009). Brock Biology of microorganisms. 12th edition. Pearson Benjamin Cummings Publishers. USA. Pp.795-796.

Nester E.W, Anderson D.G, Roberts C.E and Nester M.T (2009). Microbiology: A Human Perspective. Sixth edition. McGraw-Hill Companies, Inc, New York, USA.

Prescott L.M., Harley J.P and Klein D.A (2005). Microbiology. 6th ed. McGraw Hill Publishers, USA. Pp. 296-299.

Singleton P and Sainsbury D (1995). Dictionary of microbiology and molecular biology, 3d ed. New York: John Wiley and Sons.

Slonczewski J.L, Foster J.W and Gillen K.M (2011). Microbiology: An Evolving Science. Second edition. W.W. Norton and Company, Inc, New York, USA.

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