Which of the following is incorrect?

Options

A. Both bacteriophages and plasmids can be used as cloning vectors
B. Bacteriophages have high copy numbers of their genome within bacterial cell
C. Cloning vectors must have an Ori and MCS region
D. A good cloning vector definitely contains more than one recognition site for the restriction enzyme to be used

Answer

To determine which of the provided statements is incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding Bacteriophages and Plasmids**:
- Bacteriophages are viruses that infect and kill bacteria.
- Plasmids are circular, extra-chromosomal DNA found in prokaryotes.

**Hint**: Remember the definitions of bacteriophages and plasmids as they are crucial for understanding their roles as cloning vectors.

2. **Cloning Vectors**:
- A cloning vector must satisfy certain conditions:
- **High Copy Number**: It should be able to replicate in high quantities.
- **Easy Selection**: There should be a straightforward method to distinguish between recombinant and non-recombinant DNA.
- **Easy Linking of Foreign DNA**: It should allow for the simple insertion of foreign DNA.

**Hint**: Keep in mind the essential conditions for a good cloning vector, as they will help evaluate the statements.

3. **Evaluating the Statements**:
- **Statement 1**: Both bacteriophages and plasmids can be used as cloning vectors.
- This statement is **correct** since both can serve as vectors.

- **Statement 2**: Bacteriophages have a high copy number of their genome within bacterial cells.
- This statement is **correct** as bacteriophages can produce many copies within a host cell.

- **Statement 3**: Cloning vectors must have an ORI (Origin of Replication) and MCS (Multiple Cloning Site) region.
- This statement is **correct** because these regions are essential for replication and insertion of foreign DNA.

- **Statement 4**: A good cloning vector must contain more than one recognition site for restriction enzymes.
- This statement is **incorrect**. A good cloning vector should ideally have only one recognition site for a restriction enzyme to prevent the DNA from being cut into multiple fragments, which would complicate cloning.

**Hint**: Focus on the implications of having multiple recognition sites in a cloning vector and how it affects the cloning process.

4. **Conclusion**:
- The incorrect statement is **Statement 4**: A good cloning vector should not have more than one recognition site for restriction enzymes.

**Final Answer**: The fourth option is incorrect.