• In 1952, Joshua Lederberg coined the term plasmid.
• Extra chromosomal ,circular, double stranded DNA molecule present in bacteria.
• Codes for genes for better survival of bacteria like antibiotic resistance gene, collicin a bacterial toxin gene etc.
• Modified Plasmids are used as vectors in gene cloning..
• Insert size: up to 15 kb in size
• Eg: E.coli plasmids
Types of Plasmid vectors
Advantages
Plasmids require a bacterial origin of replication, an antibiotic resistance gene, and at least one unique restriction enzyme recognition site.
• Extra chromosomal ,circular, double stranded DNA molecule present in bacteria.
• Codes for genes for better survival of bacteria like antibiotic resistance gene, collicin a bacterial toxin gene etc.
• Modified Plasmids are used as vectors in gene cloning..
• Insert size: up to 15 kb in size
• Eg: E.coli plasmids
Types of Plasmid vectors
Advantages
- Easy to work with - Plasmids are a convenient size (generally 1,000-20,000 base pairs)
- Self replicating, stable and functional in many species.
Plasmids require a bacterial origin of replication, an antibiotic resistance gene, and at least one unique restriction enzyme recognition site.
Vector element
|
Function
|
Origin
of Replication (ORI)
|
Allows replication
inside the host
|
Multiple cloning sites
|
Contains unique restriction sites for
restriction enzymes for insertion of gene of interest
|
Antibiotic
Resistance Gene
|
Allows selection of
bacteria containing recombinant plasmid
|
Insert
|
Gene of interest with promoter enhancer etc
|
Promoter region
|
For transcription of
gene insert
|
Primer
Binding Site
|
A short single-stranded DNA sequence used as
an initiation point for PCR amplification or sequencing. Primers can be
exploited for sequence verification of plasmids
|