Fosmid

Fosmid is a type of vector used in genetic engineering and molecular biology. It is a type of plasmid, which is a small, circular piece of DNA that is separate from the chromosomal DNA, which is used to manipulate and clone DNA fragments in Escherichia coli, a type of bacteria. Fosmids are similar to cosmids, but are based on the F-factor (fertility factor) in E. coli, hence the name "fosmid".

History

Fosmids were first developed in the late 1990s as a tool for genome sequencing. They were designed to be a more stable and reliable alternative to cosmids, which were prone to rearrangements and deletions.

Structure and Function

Fosmids are typically 7-8 kilobases in size and can carry inserts of DNA up to 40 kilobases. They contain an origin of replication that is derived from the F-factor, which allows them to replicate once per cell cycle in E. coli. This makes them more stable and less prone to rearrangements than other types of vectors.

Fosmids also contain a selectable marker, usually an antibiotic resistance gene, which allows for the selection of bacteria that have taken up the fosmid. This is done by growing the bacteria on a medium that contains the antibiotic; only those bacteria that have the fosmid, and therefore the resistance gene, will be able to grow.

Applications

Fosmids are used in a variety of applications in molecular biology and genetic engineering. They are particularly useful in genome sequencing projects, as they can carry large inserts of DNA and are stable and reliable. They are also used in metagenomics, the study of genetic material recovered directly from environmental samples, as they can capture and clone large fragments of DNA from complex microbial communities.

See Also

• Vector (molecular biology)
• Plasmid
• Cosmid
• Genetic engineering
• Molecular biology
• Genome sequencing
• Metagenomics