Vector: properties, types and characteristics
- Properties of good vector
- Types of vector
- Plasmid vector
- Phage vector or Bacteriophage vector
- Artificial chromosome vector
- Shuttle vector
- It is a biological tool in rDNA technology.
- It is used for the delivery of desired foreign DNA into the host cell.
- A vector is a DNA molecule that have the ability to replicate autonomously in the host cell and into which DNA fragment to be cloned.
Properties of an ideal vector
- It should be replicate autonomously.
- A vector should be less than 10 KB in size.
- It should be easily isolated and purify.
- It should be easily introduced into the host cell.
- It should have suitable marker genes.
- Vector should consists a unique target sites and recognition sites for various restriction enzymes.
- It should have the capability to incorporate either itself or the DNA insert in the Genome of the host cell.
Types of vector
Vectors are of two types:
- Cloning vector
- Expression vector
- Cloning vectors are small piece of DNA which have the ability and used to introduce foreign gene of interest into the host cell.
- They can be stably maintained insides the host cell.
- Cloning vector are generally used to obtain multiple copies of desired foreign gene.
- Example- Plasmid, Cosmid and Phages, BACs, YACs.
- These type of vectors generally contains selectable marker, origin of replication and a restriction site.
- Expression vector is a type of vector which not only introduces a gene of interest into the host cell but also aids in the analysis of the foreign gene via relevant protein product expression.
- It is type of vector which is used to obtain or analyses the gene product, which may be RNA or protein of the inserted desired gene.
- Example- Only plasmid vector.
- Expression vector contains enhancer, promoter region, start/stop codon, transcription initiation, selectable marker, ori sites, and restriction site.
- A plasmid is a naturally occurring extrachromosomal double stranded DNA, circular DNA.
- It replicates autonomously within bacterial cell.
- Plasmid carries an origin of replication.
- Plasmid vectors are the simplest cloning vectors.
- It is most widely used for gene cloning.
Characteristics of Plasmid vector:
- It contains an ori site or origin of replication.
- It also Contain selective marker such as antibiotic resistance, blue white screening).
- Small in size (1.0 to 250kb)
- Contains multiple cloning site.
- Easily isolated from the host cell.
Examples of plasmid vectors are:
- pUC 18/19
- It is one of the first vectors to be developed by Boliver and Rodriguez in 1977.
The name pBR322 denotes the following:
- P- plasmid
- B- Boliver
- R- Rodriguez
- 322- Differentiate it from the other plasmid produced in the same laboratory E.g. – pBR325, pBR327, etc.
- It is 4363 base pair long.
It carries two sets of antibiotic resistance gene:
It contains only single or unique recognition site for 12 different restriction enzymes:
- Pst I
- Sac I
- Pvu I
- It is derivative of pBR322.
- Much smaller (~ 2.7kb).
- Ampicillin resistance gene (bla).
- ColE1 origin of replication.
- It is 2,686bp long.
The name pUC18/19 derived from:
- P- Plasmid.
- UC- university of California.
- It is a type of hybrid plasmid.
- It contains lambda phage cos sequence.
- Cosmids = cos sites + plasmid.
- Genomic size of cosmids is about 30 to 52 kb.
- If they have suitable origin of replication than they can replicate as Plasmid within the host cells, E.g.- SV40 Ori, ColE1 ori.
- It also contains selectable marker such as Ampicillin resistance gene.
- Collins and Hohn in 1978 was first to described cosmids.
- A plasmid vector which contains an origin of replication from a phage, in addition to that of the plasmid, is termed as Phagemids.
- pBlue script SK (+/-) is a type of phagemid vector of 2,958 bp derived from the pUC19.
It consists of the following:
- ColE1 ori
- Phage f1 (M13) origin of replication.
- A small portion of lacZ gene.
- MCS within lacZ Gene from Lac promoter.
- Phage T7 and T3 promoter sequence.
- Ampicillin gene for Ampicillin resistance.
Phage vector or Bacteriophage vector
- Bacteriophages are viruses that attacks bacteria.
- The Phages are simple in structure.
- It consists of DNA molecules having several gene for replication which is surrounded by Capsid.
On the basis of structure bacteria phases are of two types:
- Head and Tail Phages- E.g.: lambda phage.
- Filamentous phage- E.g.: M13 phage.
Lambda phage vectors
- Its genome size is about 48,502 bp.
- It contains origin of replication, genes for head and tail protein and enzymes for DNA replication
- It has more than one recognition sequence for almost all the restriction enzymes.
- It should be larger than 38 kb and smaller than 52 kb to packaged into phage particles.
M13 phage vectors
- M13 vectors are used to obtain single- stranded copies of cloned DNA.
- It is 6407 nucleotides long.
- It is circular and 6.4kb in size.
- M13 vector only cause infection in F+ and F’ cells.
- It is used to produce several copies of M13 mp series of vectors.
- Example- M13mp8, M13mp9 etc.
Artificial chromosome vectors
- Artificial chromosomes are circular or linear vectors.
- They are stably maintained in, usually 1 to 2 copy per cell.
There are several types of such vectors:
- Bacterial artificial chromosomes (BAC).
- Yeast artificial chromosomes(YAC).
- Mammalian artificial chromosomes(MAC).
- Human artificial chromosome (HAC).
- Shuttle vectors are created to replicates in cell of different type of species.
- They contain two origin of replication, in which one is particular for each host species, also those genes required for their replication and not provided by the host cell.
- This type of vectors are developed by recombinant techniques.
Reference and Sources
- 1% – https://www.learninsta.com/ncert-exemplar-solutions-for-class-12-biology-chapter-11/
- 1% – https://www.slideshare.net/NamrataSingh99/namrata-singh-recombinant-dna-technology <
- 1% – https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/homing-endonuclease
- 1% – https://en.wikipedia.org/wiki/Cloning_vector <
- 1% – https://link.springer.com/article/10.1007/s12185-018-2513-4
- 1% – https://www.notesonzoology.com/genetics/cloning-vectors/6-main-types-of-cloning-vectors-biotechnology/5300
- 1% – https://www.slideshare.net/ankurndri/derivatives-of-pbr322 <
- 1% – https://www.biologydiscussion.com/biology/biotechnology-useful-notes-on-traditional-and-modern-biotechnology/1411
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