Cloning vector-characteristics and types

Cloning vector-characteristics and types

Cloning vector

Cloning vector is a small DNA molecule capable of self-replication inside the host cell. Cloning vector is used for replicating donor DNA fragment within host cell.

Characteristics of a cloning vectors

  1. it must be small in size
  2. It must be self-replicating inside host cell
  3. It must possess restriction site for Restriction Endonuclease enzymes
  4. Introduction of donor DNA fragment must not interfere with replication property of the vector
  5. It must possess some marker gene such that it can be used for later identification of recombinant cell
  6. it must possess multiple cloning site

Types of cloning vectors used in gene cloning:

1. Plasmid (PBR322):

figure: plasmid PBR322

  • Example: PBR322
  • It is isolated from E.coli
  • Size: 4361 bp
  • Cloning limit: 0.1-10 kb
  • Marker gene: Ampicillin and Tetracycline resistant gene
  • Restriction site for various restriction endonucleases

2. Bacterial artificial chromosome (BAC):

figure: pUvBBAC

  • Example: pUvBBAC
  • It is artificially synthesized plasmid
  • size: 11827 bp
  • It is modification of bacterial F-plasmid
  • Cloning limit: 35-300 kb
  • Marker gene: chloramphenicol resistant gene and lactose metabolizing gene (LacZ)

3. Yeast artificial chromosome (YAC):

figure: pYAC3

  • Example: pYAC3
  • It is an artificial chromosome having yeast centromere isolated from Saccharomyces cerevisiae and ligated to bacterial plasmid
  • size: 11400 bp
  • It has telomere sequence
  • Marker: similar as for identification of yeast cell
  • Cloning limit: 100-1000 kb

4. Λ-Bacteriophase:

figure: lambda bacteriophase

  • Example: lambda genome
  • It is a phase (Virus) genome
  • size: 48502 bp
  • 1/3rd of the bacteriophase genome is non-essential, so that it can be cut, removed and replaced by donor DNA fragment during cloning
  • It can recombinant only 4-5 Kbp of donor DNA fragment

5. Expression vector:

figure: expression vector pSG5

  • Example: Eukaryotic expression vector pSG5
  • size: 4100 bp
  • An eukaryotic vector modified such a way that it can be expressed in prokaryotic cell known as expression vector
  • it allows RNA polymerase to transenecribe g

6. Cosmid:

figure: Cosmid

  • Example: super COS1
  • size: 7900 bp
  • It has combined feature of both phase and plasmid
  • Cloning limit: 30-50 kb

7. Human artificial chromosome (HAC):

  • It is artificially synthesized chromosome used to transfer human gene
  • Cloning limit; No limit, it can carry large segment of DNA




Cloning vector-characteristics and types