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R-II strain of T(4) bacteriphage cannot...

R-II strain of `T_(4)` bacteriphage cannot lyse Escherichia coli .Two of its types ,`R-II^(x) "and" R-II^(y)` were allowed to invade the bacterium which lysed because of

A

Transformation into wild type

B

Presenece of similar cistrons

C

Presence of different cistrons

D

Absence of mutation

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question regarding the R-II strain of T4 bacteriophage and its ability to lyse Escherichia coli when two types, R-II^(x) and R-II^(y), are used, we can follow these steps: ### Step-by-Step Solution: 1. **Understanding Bacteriophages**: - Bacteriophages are viruses that specifically infect bacteria. The T4 bacteriophage is a well-known example that targets E. coli. **Hint**: Remember that bacteriophages need to attach to and invade bacterial cells to replicate. 2. **Identifying the Problem with R-II Strain**: - The R-II strain of T4 bacteriophage cannot lyse E. coli on its own. This means that when R-II infects E. coli, it fails to produce the necessary proteins or enzymes required for lysis. **Hint**: Consider why a virus might fail to replicate or cause lysis in a host cell. 3. **Introducing R-II^(x) and R-II^(y)**: - The two types, R-II^(x) and R-II^(y), are variants of the R-II strain. When these two strains are allowed to infect E. coli together, they result in lysis. **Hint**: Think about the role of genetic variation and how different strains might complement each other. 4. **Mechanism of Lysis**: - The reason for the lysis when both R-II^(x) and R-II^(y) are present is that each strain produces different enzymes (proteins) necessary for the lytic cycle. R-II^(x) produces one type of enzyme, while R-II^(y) produces another. **Hint**: Consider how enzymes work together to achieve a common goal in biological processes. 5. **Role of Cistrons**: - The enzymes produced by R-II^(x) and R-II^(y) are coded by different cistrons (segments of DNA that encode a single polypeptide). The presence of different cistrons allows for the production of the necessary proteins that lead to the lysis of the bacterial cell. **Hint**: Recall that cistrons are part of the genetic code that dictates protein synthesis. 6. **Conclusion**: - Therefore, the lysis of E. coli occurs due to the presence of different cistrons in the R-II^(x) and R-II^(y) strains, which lead to the production of different enzymes that work together to cause lysis. **Final Answer**: The correct explanation for the lysis of E. coli when both R-II^(x) and R-II^(y) are present is the "presence of different cistrons."
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