THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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By tagging the DNA of the infecting bacteriophage with radioactive sulfur, the infected bacterial cell became radioactive as DNA entered and took over control.
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The protein coat of the bacteriophage was tagged with both radioactive phosphorous and sulfur and would go undetected within the infected bacterial cell since only the DNA molecule enters.
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Radioactive carbon was used to tag both DNA and the protein coat of the infecting bacteriophage which would be detected within the infected bacterial cell as both molecules enter.
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Phosphate was used to tag DNA because DNA contains phosphorus within its structure, while proteins do not, and would make the bacterial cell radioactive as DNA entered and took over control.
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Detailed explanation-1: -In their experiments, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Hershey and Chase and subsequent discoveries all served to prove that DNA is the hereditary material.
Detailed explanation-2: -How did the Hershey and Chase experiment prove that DNA, not protein, functioned in controlling genetic inheritance? (A) By tagging the DNA of the infecting bacteriophage with radioactive sulfur, the infected bacterial cell became radioactive as DNA entered and took over control.
Detailed explanation-3: -Conclusion: Resultant radioactive and non-radioactive bacteria infer that the viruses that had radioactive DNA transferred their DNA to the bacteria but viruses that had radioactive protein didn’t get transferred to the bacteria. Hence, DNA is the genetic material and not the protein.
Detailed explanation-4: -So, the correct option is ‘Phosphate was used to tag DNA because DNA contains phosphorus within its structure (specifically the backbone), while proteins do not, and would make the bacterial cell radioactive as DNA entered and took over control.
Detailed explanation-5: -Hershey and Chase found that when bacteriophages containing 32P (radioactive), were allowed to infect nonradioactive bacteria, all the infected cells became radioactive and, in fact, much of the radioactivity was passed on to the next generation of bacteriophages.