Circular single stranded DNA occurs in bacteriphage

Options

A. `T_(2),T_(4)`
B. `phixx 174,M13`
C. `T_(3),phi 6`
D. `delta,T_(5)`

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the occurrence of circular single-stranded DNA in bacteriophages. We need to identify which bacteriophage has this specific type of DNA.

2. **Identifying Bacteriophages**: The options provided likely include various bacteriophages. We need to evaluate each option to determine if they contain circular single-stranded DNA.

3. **Analyzing Bacteriophage Cy 174**:
- Cy 174 is a known bacteriophage that has a closed circular DNA molecule.
- This DNA is single-stranded, meaning it consists of only one strand rather than the typical double-stranded structure found in most DNA.

4. **Characteristics of Cy 174**:
- The closed circular single-stranded DNA in Cy 174 contains 5386 nucleotide bases.
- It encodes for 11 gene products, which indicates its functional capacity.

5. **Evaluating Other Options**:
- Bacteriophages like T2, T4, T3, and lambda 85 do not have circular single-stranded DNA. They typically have double-stranded DNA or linear forms.
- M13 is another bacteriophage that also has single-stranded circular DNA, but the question specifically asks for the one that is most commonly recognized for this characteristic.

6. **Conclusion**: Based on the analysis, the bacteriophage that has circular single-stranded DNA is Cy 174.

**Final Answer**: Circular single-stranded DNA occurs in the bacteriophage Cy 174.

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