How did Griffith's experiment demonstrate the process of bacterial transformation?
Griffith showed that when non-lethal R strain bacteria were mixed with heat-killed lethal S strain bacteria and injected into mice, the mice died and living S strain bacteria could be recovered. This indicated that the R strain had taken up genetic material from the dead S strain, transforming into the lethal form.
What is meant by 'transformation' in the context of Griffith's experiment?
Transformation refers to the ability of bacteria to uptake external DNA from their environment, resulting in changes to their genotype and phenotype.
What are the two main types of bacteria used in Griffith's experiment and how do they differ?
The two main types are the smooth (S) strain, which is lethal due to its capsule, and the rough (R) strain, which is non-lethal because it lacks the capsule.
What happened when Griffith injected mice with only the S strain bacteria?
The mice died because the S strain is lethal.
What was the result when mice were injected with only the R strain bacteria?
The mice survived because the R strain is non-lethal.
What was the outcome when Griffith injected mice with heat-killed S strain bacteria?
The mice survived because the heat-killed S strain could not cause disease.
What surprising result did Griffith observe when he injected mice with a mixture of R strain and heat-killed S strain bacteria?
The mice died, and living S strain bacteria could be recovered from them.
What conclusion did Griffith draw from the experiment where both R strain and heat-killed S strain were injected together?
He concluded that the R strain bacteria had transformed by uptaking genetic material from the dead S strain, becoming lethal.
Why was Griffith's experiment important for the understanding of genetic material?
It showed that some genetic factor could be transferred between bacteria, laying the groundwork for identifying DNA as the genetic material.
Who later identified the 'transforming substance' in Griffith's experiment as DNA?
Oswald Avery, Colin MacLeod, and Maclyn McCarty identified the transforming substance as DNA.