Question

What is the biggest disadvantage of plasmids?

• A. They work only in bacteria and fungi
• B. Restriction enzymes can cut it
• C. DNA segments bigger than 7 Kbp cannot be inserted
• D. Their functioning is not yet fully studied

Answer 1

The correct option is C DNA segments bigger than 7 Kbp cannot be inserted

Since the size of the plasmid has to remain smaller than the cellular DNA, the gene that is intended to be inserted into the plasmid cannot be very large in size. Maximum size permissible in a plasmid vector is 7 Kbp (kilobase pair).

However, there are certain genes that are much longer than 7 kilobase pairs. Plasmids cannot be used when such large genes need to be transferred into a host cell.