Plasmids pBR322 and pUC18/19: Cloning Vectors
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Plasmids pBR322 and pUC18/19
pBR322
pBR322, developed in 1977, is a foundational plasmid in molecular biology. Key features include:
- Size: ~4,361 base pairs (bp)
- Origin of Replication: Allows independent replication within bacteria.
- Selection Markers:
- ampR: Confers ampicillin resistance.
- tetR: Confers tetracycline resistance.
- Cloning Sites: Multiple sites for inserting foreign DNA.
- Applications: Gene cloning, expression, and manipulation.
pUC18/19
pUC18/19, derived from pBR322 in the early 1980s, simplifies cloning. Key features include:
- Size: ~2,686 bp
- Origin of Replication: High-copy-number pMB1 ori for increased yield.
- Selection Marker:
- lacZ: Beta-galactosidase gene; enables blue/white screening for insert identification.
- Cloning Sites: Multiple cloning site (MCS) for easy DNA insertion.
- Applications: Cloning, sequencing, and gene expression.
Summary
- pBR322: Early plasmid; ampicillin and tetracycline resistance; used for cloning and selection.
- pUC18/19: Derived from pBR322; high-copy replication; lacZ screening; versatile cloning sites; efficient cloning and expression.
Both plasmids are essential tools in genetic research and biotechnology.