pBR322 , which is frequently used as a vector for cloning gene in E, coil is a/an.

Options

A. original bacterial plasmind
B. modified bacterial
C. viral genome
D. transposon

Answer

To answer the question regarding what PBR322 is, we can follow these steps:

### Step-by-Step Solution:

1. **Identify PBR322**:
- PBR322 is a plasmid that was developed for use in molecular cloning. It is derived from the bacterium Escherichia coli (E. coli).

2. **Understand its Modification**:
- PBR322 is not a naturally occurring plasmid; it has been genetically modified. This modification includes the introduction of specific genes and sequences that allow it to function effectively as a cloning vector.

3. **Recognize its Components**:
- PBR322 contains genes for antibiotic resistance (specifically ampicillin and tetracycline), which allows for the selection of transformed cells.
- It also has an origin of replication (ORI) that enables it to replicate within the host cell.

4. **Determine the Classification**:
- Since PBR322 is a modified version of a bacterial plasmid, it falls under the category of a "modified bacterial plasmid." It is not a viral genome or a transposon.

5. **Conclude the Answer**:
- Therefore, the correct classification for PBR322 is that it is a **modified bacterial plasmid**.

### Final Answer:
PBR322 is a modified bacterial plasmid.