Question

Bacterial cloning vectors and bacterial expression vectors are differentiated by the presence of

• A. antibiotic resistance gene cassette
• B. origin of replication
• C. promoter and ribosome-binding site
• D. unique restriction sites

Hint:

Cloning vector = replication only; Expression vector = replication + protein expression.

Answer 1

The Correct Option is C

Step 1: Cloning vector.
A cloning vector is designed to replicate DNA fragments. It contains an origin of replication, selection markers, and restriction sites, but it does not express the gene product.
Step 2: Expression vector.
An expression vector is specialized for gene expression inside bacteria. It must contain additional regulatory elements such as a strong promoter and ribosome-binding site to allow transcription and translation of the inserted gene.
Step 3: Differentiate.
Thus, the presence of a promoter and ribosome-binding site distinguishes expression vectors from simple cloning vectors.
Final Answer: \[ \boxed{\text{Expression vectors contain promoter and ribosome-binding site.}} \]