Question

All expression vectors are cloning vectors and vice versa. Expression vectors have at least the regulatory sequences i.e., promoters, operators, ribosomal binding sites, etc. having optimum function in the chosen control but not origin of replication.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (D)

If both assertion and reason are false

Answer 2

All vectors used for propagation of $DNA$ inserts in a suitable host are called cloning vectors. But when a vector is designed for the expression i.e., production of the protein specified by the $DNA$ insert, it is termed as expression vector, Expression vectors need regulatory machinery suitable for the host, e.g., if an eukaryotic gene is to be expressed in prokaryotes, the expression vectors should contain gene without introns because prokaryotes lack introns removal machinery for transcripts. But all vectors, including expression vectors must contain 'origin of replication' so that they can replicate when the host cell divides and their presence is ensured in all progeny.