Phagemid or phasmids are DNA-based cloning vectors showing both plasmid and bacteriophage attributes. In addition to the origin of plasmid replication, it carries vectors. Cosmids are a type of hybrid plasmid containing a lambda phage cos sequence, widely used in cloning vectors in genetic engineering.

Cosmid is different from Phagemid in the type of sequence contained. Cosmids comprise a cos site and a plasmid, which is why it is a hybrid vector. On the other hand, Phagemids are plasmids containing an F1 origin with F1 phage – replication.

Cosmid

• They are a type of hybrid plasmids containing a lambda phage cos sequence
• Often, these are used as a cloning vector, and can be used in building genomic libraries
• It contains 37-52 kb of DNA, based on the size of bacteriophage packaging
• Under apt origin of replication (ori), it can replicate as a plasmid
• It also comprises a gene for selection frequently for transformed cells to be identified on a medium with the antibiotic

Phagemid

• Phasmid or phagemids are DNA-based cloning vectors having both bacteriophages and plasmid traits
• Along with the origin of plasmid replication, the vectors carry an origin of replication obtained from the bacteriophage
• Phagemids, unlike plasmids, vary in having the ability to be packaged into the capsid of bacteriophage, as they possess a genetic sequence signaling for packaging
• They find application in different streams of biotechnology (Phage display)

Key Difference between Cosmid and Phagemid

The table below depicts the difference between Cosmid and Phagemid.

You read some differences between Cosmid and Phagemid.

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