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- Hello! We are Avery Macleod, and McCarty and we are here to talk you through our favorite experiment.
- After hearing about Fredrick Griffiths experiments on bacterial transformation my friends and I decided we were interested in the two different strands of bacteria used in that experiment.
- We wanted to learn more about what caused transformation in cells. We used Streptococcus pneumoniae, a smooth strand and a rough strand.
- The smooth strand had a polysaccharide coat which gives it a smooth, shiny coat. This coat is what allows the bacteria to cause illness. The rough strand lacks that smooth coating and does not cause illness.
- The previous experiments by Griffith showed that if you use hat to kill the smooth strand and injected mice with a living rough strand and the dead smooth strand the mice would still die of pneumonia! Extractions from the mice showed the smooth strand was present despite being killed before entering the mice.
- Then we mixed the samples with several different enzymes, each in their own test tube. The enzymes included : Trypsin, DNase, RNase, Lipase, and a Polysaccharide degrading enzyme known as Protease.
- We started by using heat to kill large colonies of the smooth strand and then using several different processes to purify this sample.
- After incubation we placed the material from the test tubes onto petri dishes and examined them to see if the rough or smooth strand was present.
- After the enzyme was placed with the killed and purified smooth strand the test tubes were inoculated with live rough strand and placed in an incubator.
- The enzyme would destroy the proteins they were designed to prevent so then they could not be "transformed".
- The only petri dish that the rough strain and none of the smooth strain was the DNase. This showed us that DNA was what would be transmitted and transform the other cells!
- This means if the smooth strand was present the protein we were testing for was not responsible for the transforming property of cells. 
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