Answer:
The bacterial pellet would have contained both isotopes, making it unclear which substance was the genetic material.
Explanation:
Bacteriophages are viruses that infect bacteria, those of the even T series (T2, T4 and T6). Hershey and Chase work with viruses that attack the enterobacteria Escherichia coli. Bacteriophages consisting of DNA viruses with a protein coat (capsid)
The infection process is that the virus injects its DNA into the bacteria. This viral DNA is inserted into the bacteria's DNA, which begins to make new copies (offspring) of the virus. After 25 minutes of injecting the DNA, the bacteria (host cell) explode, releasing hundreds of new bacteriophages. Since phages have only DNA and proteins, they were the appropriate tool to reveal the chemical nature of the hereditary material.
In 1952, Hershey and Chase designed an experience to find out if the inheritance was communicated by DNA or by proteins. They used radioactive labeling techniques to build two different types of phage populations (both T2). A population of phages grew in a medium containing the radioactive isotope S35. The S35 marks the proteins that contain the amino acids cysteine or methionine and therefore this population contains radioactive proteins and not radioactive DNA, since the DNA does not contain sulfur. The second population of virus grew in a medium containing P32. P32 marks nucleic acids, but not proteins, so that this population contains radioactive DNA and non-radioactive proteins. Both types of viruses were used separately to infect susceptible E. coli cells.
