Question

pBluescript II KS is a

• A. Plasmid
• B. Cosmid
• C. Phagemid
• D. Artificial chromosome

Hint:

• Phagemid A plasmid vector that also contains an origin of replication from a filamentous bacteriophage (e.g., M13, f1).
• Allows for replication as a double-stranded plasmid and, upon infection with a helper phage, packaging of single-stranded DNA into phage particles.
• Useful for ssDNA production for sequencing, mutagenesis, etc.
• pBluescript is a common example.

Answer 1

The Correct Option is C

pBluescript II KS is a type of vector used in molecular cloning. It is classified as a phagemid. Phagemids are vectors that carry the origins of replication of both plasmids and bacteriophages, allowing them to be replicated in bacteria as plasmids or packaged into phage particles when helper phage is present. This dual nature makes them highly versatile in genetic engineering.

The other options can be distinguished as follows:

• Plasmid: A small, circular DNA molecule independent of chromosomal DNA, commonly used for cloning, often lacking the specific phage origin found in phagemids.
• Cosmid: A hybrid plasmid that contains a Lambda phage cos site, allowing it to be packaged into phage particles for infection and can carry larger DNA fragments compared to ordinary plasmids.
• Artificial Chromosome: A large synthetic chromosome used to clone DNA fragments larger than those handled by plasmids and cosmids, such as BACs (Bacterial Artificial Chromosomes) and YACs (Yeast Artificial Chromosomes).

Therefore, the correct classification for pBluescript II KS is Phagemid.