Question

Which of the following is not a desirable feature of a cloning vector?

• A. Presence of origin of replication
• B. Presence of a marker gene
• C. Presence of single restriction enzyme site
• D. Presence of two or more recognition sites

Answer 1

The Correct Option is D

In molecular biology, a cloning vector is an essential tool designed to replicate foreign DNA inserted into a host cell. When selecting an ideal cloning vector, the following characteristics are generally desirable:

1. Presence of origin of replication: This feature allows the vector to replicate independently within the host cell, making it essential for the propagation of the inserted genetic material.
2. Presence of a marker gene: Marker genes typically confer a selectable trait, such as antibiotic resistance. This allows researchers to easily identify cells that have taken up the vector.
3. Presence of a single restriction enzyme site: Having a single site for a restriction enzyme ensures that the vector can be linearized and recombined where necessary, which facilitates the insertion of foreign DNA without unwanted fragmentation.

A key aspect to note is the presence of two or more recognition sites for cloning vectors:

Vectors with multiple recognition sites for the same restriction enzyme may lead to complications in inserting foreign DNA since the enzyme can cut at multiple sites, potentially fragmenting the vector and making the cloning process inefficient and less predictable. Therefore, this is not a desirable feature for a cloning vector.

Therefore, the correct option is: Presence of two or more recognition sites.