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Frederick Griffith

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birch
12 diapositives · 413 Views · Jul 27, 2014

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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  1. Key Figures to the discovery of the Double Helix Frederick Griffith

  2. 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)

  3. 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

  4. The Experiment • INSERT FARAH’S DIAGRAM

  5. 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.

  6. 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!

  7. 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

  8. 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

  9. 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.

  10. Impact on the Science community • enabled others to point out that DNA was the molecule of inheritance

  11. 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

  12. The End • Oh and by the way… he never did find the vaccine Done by: Deborah, Durkasri, Elaine, Farah, FengYue