Which of following feature is not necessary for cloning vector

Options

A. Origin of replication
B. High copy number
C. Selectable marker
D. Cloning sites

Answer

To determine which feature is not necessary for a cloning vector, let's analyze the options provided: origin of replication, copy number, selectable markers, and cloning site.

### Step-by-Step Solution:

1. **Understand Cloning Vectors**: Cloning vectors are DNA molecules used to transport foreign genetic material into a host cell. They are essential tools in biotechnology for gene cloning.

2. **Identify Necessary Features**:
- **Origin of Replication**: This is crucial because it allows the cloning vector to replicate within the host cell, ensuring that the inserted DNA is copied during cell division.
- **Selectable Markers**: These are important for identifying and selecting the cells that have successfully taken up the cloning vector. They often confer resistance to antibiotics or allow for the expression of a detectable phenotype.
- **Cloning Site**: This is the specific location on the vector where the foreign DNA can be inserted. It must be present for the cloning process to occur.

3. **Evaluate Copy Number**: The copy number refers to how many copies of the vector can exist within a single host cell. While a higher copy number can be beneficial for producing more of the cloned DNA, it is not strictly necessary for the cloning process itself. Cloning can still occur with a low copy number, as long as the other essential features are present.

4. **Conclusion**: Among the options given, the feature that is not necessary for a cloning vector is the **copy number**.

### Final Answer:
The feature that is not necessary for a cloning vector is **copy number**.