GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the protein coat from pathogenic cells was able to transform nonpathogenic cells.
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heat-killed pathogenic cells caused pneumonia.
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some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.
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the polysaccharide coat of bacteria caused pneumonia.
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Detailed explanation-1: -So, the correct option is ‘some heat-stable chemical from S cells was transferred to R cells to transform them into S cells’.
Detailed explanation-2: -In his work with pneumonia-causing bacteria and mice, Griffith found that a. the protein coat from pathogenic cells was able to transform nonpathogenic cells.
Detailed explanation-3: -To find out, Griffith ran a series of experiments. First, Griffith took a culture of the S strain, heated the cells to kill them, and then injected the heat-killed bacteria into laboratory mice. The mice survived, suggesting that the cause of pneumonia was not a toxin from these disease-causing bacteria.
Detailed explanation-4: -Experiment 4: Griffith mixed his heat-killed, disease-causing bacteria with live, harmless bacteria and injected the mixture into the mice. The mice developed pneumonia and died. Griffith concluded that the heat-killed bacteria passed their disease-causing ability to the harmless strain.
Detailed explanation-5: -Experiment: Griffith injected both S and R strains to mice. The one which was infected with the S strain developed pneumonia and died while that infected with the R strain stayed alive. In the second stage, Griffith heat-killed the S strain bacteria and injected into mice, but the mice stayed alive.