S Strand Of Streptococcus Pneunomoniae example essay topic

April 4, 2003 Biology P. 7 Avery, MacLeod, and McCarty Problem Statement What molecule allows the transfer of genetic information to transform Streptococcus pneunomoniae from a non virulent (R) strand to a virulent strand (S) of Streptococcus pneunomoniae? Background In 1928 an army doctor named Fred Griffith tried to develop a vaccine against Streptococcus pneunomoniae which caused a type of pneumonia. Griffith had no success in creating a vaccine, but he found out that the bacteria had two different forms. One form was the smooth (S) form and the other was the rough form (R). The rough (R) form of the bacteria was not harmful, but the smooth (S) form was lethal. He created an experiment in which he Heat-Killed the lethal smooth form of the bacteria and mixed them with the harmless rough form.

When he did this he discovered that the rough form of the bacteria was "transformed" into the lethal smooth (S) form of the bacteria. Hypothesis If S, trypsin, chymotrypsin, and RNase (enzymes which break down sugars, proteins, and RNA) are combined with the S strand of Streptococcus pneunomoniae and it continues to transform the R strand into the S strand then DNA is the molecule that holds genetic information (DNA is the transformation principle). Variables Extraneous variables - Sterile equipment (droppers, test tubes, etc.) - Sterile enzyme solutions - Same temperature - Same humidity - Same ventilation - Same air - Same enzymes used - Same amount of time for enzymes to react - Same techniques used to mix enzymes Experimental variable - The ability of the S strand to transform the R strand into the S strand. Materials - Detergent (for losing) - Enzyme S - Enzyme Trypsin - Enzyme Chymotrypsin - Enzyme RNase - Enzyme DNase - Alcohol (for precipitation of nucleic acids) - Test tubes - Droppers - Microscope - Wet slides - Bunsen burner - Live S strand Streptococcus pneunomoniae - Live R strand Streptococcus pneunomoniae Procedure 1. Put S strands of Streptococcus pneunomoniae into a test tube.

2. Heat-kill the S strands of Streptococcus pneunomoniae with a Bunsen burner. 3. Add detergent to lyse the heat-killed S strand. 4. Add enzyme S to eliminate to sugar coat within the test tube.

5. Add enzyme Trypsin and Chymotrypsin to break down proteins within the test tube. 6. Mix the S strand lysate with live R strand Streptococcus pneunomoniae. 7. Observe the reaction and record information to see if a transformation of the R strand into an S strand takes place.

8. After the observation add alcohol to the S strand lysate to precipitate nucleic acids (DNA and RNA) 9. Add RNase to break down RNA. 10. Mix the S strand lysate with live R stand Streptococcus pneunomoniae. 11.

12. After the observation add DNase to the S strand lysate to break down the DNA. 13. 14. Conclusion A conclusion about the problem was reached through the results of the experiment and the molecule that contains genetic information which allows the transfer of genetic information to transform Streptococcus pneunomoniae from a non virulent (R) strand to a virulent strand (S) of Streptococcus pneunomoniae.