Which one is cloning plasmid, not an expression plasmid

Options

A. pBAD - 18 - Cam
B. pBCSK
C. pUC 19
D. pET

Answer

To determine which option is a cloning plasmid and not an expression plasmid, we can analyze the given options based on their characteristics:

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Cloning Plasmid**: A plasmid that is primarily used to clone DNA fragments. It does not necessarily have the components required for gene expression.
- **Expression Plasmid**: A plasmid that contains sequences necessary for the expression of a gene, including promoters and terminators.

2. **Analyze the Options**:
- **PBAD**: This is an expression plasmid that contains the PBAD promoter, which is used for the regulated expression of genes in bacteria.
- **18-CAM**: This is also an expression plasmid that is designed for expressing proteins in bacterial systems.
- **PBC-SK**: This plasmid is used for cloning but can also have expression capabilities, making it a hybrid.
- **PUC-19**: This is a well-known cloning plasmid that does not contain the necessary elements for gene expression, making it a pure cloning vector.
- **PET**: This is an expression plasmid that contains strong promoters for high-level expression of proteins.

3. **Identify the Correct Answer**:
- Among the options, **PUC-19** is the only plasmid that is strictly a cloning plasmid and does not have the components for gene expression.

4. **Conclusion**:
- Therefore, the correct answer to the question "Which one is cloning plasmid, not an expression plasmid?" is **PUC-19**.