PBR 322 is an artificial gene vector which does not have

Options

A. Amphiciline marker gene
B. Cos site
C. Restriction site for cla I enzyme
D. Ori

Answer

**Step-by-Step Solution:**

1. **Understanding PBR322**: PBR322 is a well-known artificial plasmid vector used in molecular cloning. It contains several important features that allow for the insertion of foreign DNA and the selection of transformed cells.

2. **Identifying Key Components**: The PBR322 vector includes:
- **Restriction sites** for various endonucleases (e.g., HindIII, ClaI, EcoRI, PvuII, BamHI, SalI).
- **Origin of Replication (ORI)**, which is essential for the plasmid to replicate within a host cell.
- **Selectable marker genes**, such as those for antibiotic resistance (e.g., ampicillin and tetracycline).

3. **Analyzing the Options**: The question asks what PBR322 does not have. The options typically include various genetic elements or features.

4. **Recognizing the Absence of the "cos" Site**: The "cos" site is a specific sequence found in certain bacteriophages (like lambda phage) that is involved in the packaging of DNA into phage particles. PBR322 does not contain a "cos" site, as it is not derived from a bacteriophage but is a plasmid.

5. **Conclusion**: Therefore, the correct answer to the question is that PBR322 does not have a "cos" site.

**Final Answer**: PBR322 is an artificial gene vector which does not have a "cos" site.

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