Which of the following step shows transformation w.r.t. Griffith Experiment.

Options

A. Mouse inoculated with encapsulated bacteria
B. Mouse inocualted with non encapsulated bacteria
C. Mouse inoculated with heat killed encapsulate bacteria
D. Heat killed encapsulated and non encapsulated bacterial inoculation

Answer

**Step-by-Step Solution:**

1. **Understanding Griffith's Experiment**:
- Frederick Griffith conducted experiments using two strains of the bacterium *Streptococcus pneumoniae*: the S-strain (virulent) and the R-strain (non-virulent). The S-strain has a smooth polysaccharide coat that protects it from the host's immune system, while the R-strain lacks this coat.

2. **Inoculation with S-strain**:
- When mice were inoculated with the S-strain, they died. This indicates that the S-strain is virulent.

3. **Inoculation with R-strain**:
- When mice were inoculated with the R-strain, they survived. This shows that the R-strain is non-virulent and does not cause disease.

4. **Inoculation with Heat-Killed S-strain**:
- Mice inoculated with heat-killed S-strain survived. This indicates that the heat treatment killed the bacteria, rendering it non-virulent.

5. **Inoculation with Heat-Killed S-strain and Live R-strain**:
- When mice were inoculated with a mixture of heat-killed S-strain and live R-strain, the mice died. This was the crucial observation that led to the conclusion of transformation.

6. **Conclusion of Transformation**:
- The death of the mice in the last experiment indicated that some "transforming principle" from the heat-killed S-strain was taken up by the live R-strain, allowing it to produce the smooth polysaccharide coat and become virulent.

7. **Identifying the Correct Option**:
- The option that describes the transformation process is D: "Heat killed encapsulated and non-encapsulated bacterial inoculation." This is because it was the combination of heat-killed S-strain (encapsulated) and live R-strain (non-encapsulated) that resulted in the transformation of the R-strain to virulent.

**Final Answer**: D. Heat killed encapsulated and non-encapsulated bacterial inoculation.

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