Key figures to the discovery of the double helix
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Key Figures to the discovery of the Double Helix. Frederick Griffith. Introduction. In 1928 an army medical officer named Frederick Griffith was trying to find a vaccine against streptococcus pneumoniae (the bacteria that causes pneumonia, a lung disease). Significance.

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Frederick Griffith

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Key figures to the discovery of the double helix

Key Figures to the discovery of the Double Helix

Frederick Griffith


Introduction

Introduction

  • In 1928 an army medical officer named Frederick Griffith was trying to find a vaccine against streptococcus pneumoniae(the bacteria that causes pneumonia, a lung disease)


Significance

Significance

  • But instead made a breakthrough in the world of heredity!

  • He performed the first experiment which suggested that protein was not the genetic material


The experiment

The Experiment

  • INSERT FARAH’S DIAGRAM


The experiment1

The Experiment

  • He did four experiments in which he injected strands of bacteria into mice, one strand that was harmless (R) and one that was harmful (S).

  • In his first experiment, he injected the live R bacteria cells into a group of mice and the mice lived.

  • In his second experiment, he injected the live S bacteria cells into a group of mice and mice died.


The experiment2

The Experiment

  • In his third experiment, he killed the harmful S cells with extreme heat, and then injected the dead S cells into a group of mice and the mice lived.

  • In his last experiment, he added live R cell (which are harmless) to the already dead heat-killed S cells, and then injected it into a group of mice, but the mice died!


Results

Results

  • even though he had killed the S cells, he hadn’t destroyed their hereditary material, which was the one part that caused the disease!

  • the harmless R cells had used the information from the hereditary material of the dead S cells and became harmful

  • he called this hereditary transformation


Conclusions

Conclusions

  • The Live R had been transformed into Live S by some “transforming factor”

  • the genetic information in the heat-killed virulent bacteria survived the heating process and was somehow incorporated into the genetic material of the non-virulent strain to cause them to become virulent


Conclusion

Conclusion

  • But Griffith knew that heat denatures protein, so he suggested that the genetic material must be something else.

  • However, his results did not specifically point to DNA as a possibility.


Impact on the science community

Impact on the Science community

  • enabled others to point out that DNA was the molecule of inheritance


References

References

  • nphsscience.com/barra/classes/bio_h/handout_dna_scientist.doc

  • http://library.thinkquest.org/27819/ch6_2.shtml

  • http://answers.yahoo.com/question/index?qid=20081208174545AAl7c01


The end

The End

  • Oh and by the way… he never did find the vaccine

Done by: Deborah, Durkasri, Elaine, Farah, FengYue


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