Fred Griffith studied two strains of Streptococcus pneumonia, one that causes a lethal infection when injected into mice, and a second that is harmless.He observed that pathogenic bacteria that have been killed by heating can no longer cause an infection.But when these heat-killed bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a mouse.What did Griffith conclude from this experiment?

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Griffith concluded that the heat-killed pathogenic bacteria "transformed" the harmless strain into a lethal one. This transformation suggested that genetic material from the dead pathogenic strain had been taken up by the live harmless strain, changing its phenotype and making it pathogenic. This experiment provided evidence for the concept of bacterial transformation and the idea that genetic material can be transferred between cells.

Fred Griffith Studied Two Strains of Streptococcus Pneumonia, One That