More Murders of the Streptococcus Bacterium: The Avery-MacLeod-McCarty Experiment
The Avery-MacLeod-McCarty experiment was a sequel to the Griffith experiment in that it tried to find the mysterious "transforming principle." (This was the name given to the mysterious entity that transformed the harmless R strain into the harmful S strain. In my previous article, I referred to this as an "instruction manual," as the transforming principle harbors the information necessary to induce expression of S strain characteristics.
The procedure is as follows: first, the cell lysate of the heat-killed S strain is placed into several containers. (One dish per experimental group.) Each dish is treated with a different enzyme. These enzymes have been created or isolated such that they specifically target one kind of macromolecule. Examples include RNase (to break down RNA), trypsin (to degrade proteins), polysaccharide-degrading enzymes such as amylase, DNase (to break down DNA), lipase (to break down fats), and other specific degradative enzymes. The S-strain cell lysate would be subjected to each of these treatments in the various experimental groups. The treated solution would then be inserted into the live R strain. If transformation was successful, the R strain would be converted to the S strain, and the mouse would die. If the mouse died, the enzyme that the lysate was treated with did NOT target the transforming principle, since the transforming principle remained intact. This process eliminates macromolecules strategically.
Scientists hypothesized that the trypsin experimental group would not successfully transfer, meaning that they thought protein was the transforming principle. However, the DNase was actually unsuccessful for transfer, bolstering the case for DNA being the elusive transforming principle.
Although this evidence is pretty compelling, scientists were still skeptical. So, this series isn't over yet! In the meanwhile, watch this video to review how this experiment worked: https://www.youtube.com/watch?v=N72Cle8xST0. It's got some awesome visuals!
Stay sciencing :)))
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