Difference between pBR322 and pUC19

Both pBR322 andpUC19 are popular plasmids that are used as E.Coli cloning vectors. The prefix ‘p’ in both the vectors denotes ‘plasmid’. They have several restriction sites. Let’s look at the difference between these two vectors.

pBR322

It was the first artificial cloning vector created in the laboratory by Francisco Bolivar and Raymond L.Rodriguez. Also, pBR322 is bigger in size compared to its pUC counterparts. Thus, they have a slower rate of replication. This E.Coli cloning vector has the origin of replication (ori), restriction site and also antibiotic-resistant genes.

pUC19

It is an artificial cloning vector created by Joachim Messing and his co-workers. It is a circular double-stranded DNA similar to the pBR322. But, pUC19 is widely used in molecular techniques due to its high copy number. They are smaller in size, and hence their rate of replication is high.

Explore: Recombinant DNA Technology

Difference between pBR322 and pUC19

pBR322

pUC19

This vector is 4361 base pairs in length.

This vector is 2686 base pairs in length.

The bla gene encodes for ampicillin resistance (AmpR), and the tetA gene encodes for tetracycline resistance (tetR).

The lacZ gene codes for ꞵ galactosidase. This vector also encodes for AmpR.

It provides approximately 20 plasmid copies for a cell (low copy number).

It provides approximately 500 to 700 copies per cell (high copy number).

Its molecular weight is 2.83×106 daltons. It is bigger in size than pUC 19.

Its molecular weight is 1.75×106 daltons.

The restriction sites in pBR322 are – HindⅢ, BamHⅠ, SalⅠ, PstⅠ, PvuⅡ, PvuⅠ, ClaⅠ and EcoRⅠ.

The restriction sites in pUC19 are – HindⅢ, BamHⅠ, SalⅠ, SmaⅠ, SacⅠ, KpnⅠ, XbaⅠ, PstⅠ, SphⅠ and EcoRⅠ.

Also see: Cloning vector.

Frequently Asked Questions

What is a cloning vector?

It is a small DNA fragment that has the stability to act as a vector/vehicle for cloning purposes. Usually, foreign DNA is inserted into the cloning vector. After reaching the target cell, they can replicate and integrate with the target or host. These vectors can be of a virus cell, bacterial cell or even plasmid of a bacterial cell. Bacteriophages also act as a cloning vector.

What are natural cloning vectors?

Plasmids and bacteriophages are commonly used natural cloning vectors. The Ti plasmid is naturally found in the Agrobacterium tumifecians (plant bacterium). Some plasmids are artificially created to act as vectors (pBR322 and pUC19). Artificial vectors have a better replication rate than natural cloning vectors.

What is the abbreviation of ‘pBR322’?

The ‘p’ denotes it is a plasmid cloning vector. The ‘BR’ stands for Boliver and Rodriguez. Finally, the number 322 segregates this vector from the other trial vectors they have created in the laboratory.

Also Read: Plasmid

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