29 May 2011


Enzymes used in Recombinant genetic material equipment

Restriction Enzymes

For cloning of genetic material, the genetic material is graze by point sites, which are recognizable and cleaved by point enzymes. These enzymes are renowned as restriction enzymes. These restriction enzymes recognize fleeting sequences of dual stranded genetic material as targets pro cleavage. Different enzymes recognize uncommon but point sequences, all ranging from 4-8 corrupt pairs. The enzymes are named by a three epistle (or four letter) abbreviation with the intention of identifies their origin e.G. AluI is derived from Arthrobacter luteus, EcoRI is derived from E.Coli, HpaI is derived from Haemophilus parainfluenzae

Besides cleavage, modification in the form of methylation is furthermore brought in this area by approximately enzymes called modification enzymes now and again furthermore called “methylases”. Different species of bacteria contain their own sets of restriction enzymes and corresponding methylases. Depending on the uncommon modes of proceedings, the restriction enzymes be inflicted with been classified into three foremost classes- type I, type II, type III. Out of these, type II restriction enzymes are used in recombinant equipment as they can be used in vitro to recognize and smite with in point genetic material sequences ordinarily consisting of 4-8 nucleotides.

Genetic material ligases
These enzymes form phosphodiester bonds linking the adjacent molecules and, covalently associations two party fragments of dual stranded genetic material. The generally commonly used enzyme pro cloning conduct experiment is T4 genetic material ligase.

Alkaline phosphatase

The enzyme alkaline phosphatase (AP) removes the phosphate assemble from the 5’ aim of a genetic material molecule leaving a emancipated 5’ hydroxyl assemble therefore it is used to prevent uninvited self-ligation of vector genetic material molecules in cloning procedures. This enzyme is isolated from bacteria (BAP) or calf intestine (CAP).
Cloning vectors pro Recombinant genetic material

Vectors are the vehicles used to involve a foreign genetic material sequence into a agreed host cell. A vector must be inflicted with a) origin of duplication, b) a selectable marker to excellent the host cells containing the vector from amongst persons which sort out not be inflicted with the vector, c) lone unique restriction endonuclease recognition locate to enable foreign genetic material to be inserted into the vector in order to generate a recombinant genetic material molecule and, d) it must be relatively small in size.

Plasmids as vectors

Plasmids are defined as sovereign elements, whose genomes exist in the cell as extrachromosomal units. They are self replicating, circular duplex genetic material molecules bestow in digit of copies in a bacterial cell, mushroom cell or in organelles in eukaryotic cells. These genuinely occurring plasmids be inflicted with been modified to supply as vectors in the laboratory.

PBR322 vectors

One of the generally commonly used cloning vector in gene cloning procedures is pBR322 (named with Bolivar and Rodriguez who constructed this) derived from E. Coli plasmid ColE1. It is 4,362 bp genetic material with genes pro resistance hostile to two antibiotics- tetracycline and ampicillin. It was constructed with several alterations and modifications in earlier cloning vectors.

PUC vectors

The plasmids belonging to pUC run of vectors are 2,700 bp long with ampicillin resistance gene, the origin of duplication derived from pBR322 and the lac Z gene derived from E.Coli. When the genetic material fragments are cloned in this region of pUC, the lac gene is inactivated.

Yeast plasmid vectors

Special vectors used to introduce genetic material segments in mushroom cells or a eukaryotic cell is being used to develop genetically engineered mushroom cells. E.G. YIp or mushroom integrative plasmids which allows transformation by crossing ended and be inflicted with thumbs down origin of duplication. YEp or mushroom episomal plasmids involve 2 micron genetic material sequence counting the origin of duplication and rep gene. These vectors be inflicted with been widely used to study mushroom genome.

Shuttle vectors
The vectors containing two types of origin of duplication which helps them to exist in both eukaryotic cell as well as E.Coli are renowned as ferry vectors. E.G.Yep vector.
Retriever vectors
A rank of vectors which are used to retrieve point genes from the habitual DNA of an organism like mushroom through recombination. They are very helpful in isolation of genes from mushroom pro molecular experiments like sequencing.

Vectors based on bacteriophages

Bacteriophages are viruses with the intention of infect bacterial cells by injecting their genetic material into these cells. They are used as vectors since they be inflicted with a linear genetic material molecule, which generate two fragments with fissure. These are shortly tied with foreign genetic material to generate chimeric phage particle. The injected genetic material is selectively replicated and articulated in the host cell ensuing in a digit of phages which burst made known of the cell (lytic pathway) and additional infect the neighbouring cells. E.G. M13 , Lambda ( )

Cosmids as vectors

Cosmids are plasmid particles into which point genetic material sequences like cos sites of phage lambda are inserted and they are constructed by combining particular figure of plasmids and the ‘cos’ sites of phage lambda. The benefit of the using cosmids pro cloning is with the intention of its efficiency is distinguished to yield a complete genomic store of 10(6)-10(7) clones from single 1 microgrm of slot in genetic material.

Phagemids as vectors

Phagemids are prepared artificially by combining facial appearance of phages with plasmids. E.G. PBluescript II KS is derived from pUC19 and is 2961 bp long.

BAC Vectors

BACs or Bacterial Artificial Chromosomes are vectors based on the natural, extra-chromosomal plasmid of E.Coli- the productiveness or F-plasmid, and are being used in genome sequencing projects. A BAC vector contains genes pro duplication and maintenance of the F-factor, a selectable marker and cloning sites and can accommodate up to 300-350 kb of foreign genetic material.

Plant and creature viruses as vectors

A digit of sow and creature viruses can furthermore be used as vectors pro introducing foreign genes into cells and/or pro gene amplification in host cells. Plant viruses like Gemini viruses, cauliflower mosaic virus or CaMV and tobacco mosaic virus /TMV) are three assemble of viruses with the intention of be inflicted with been used as vectors pro cloning of genetic material segments. CaMV has a dual stranded genetic material molecule, 8kbp in size which infects the members of Cruciferae family tree. Geminiviruses are a assemble of single stranded genetic material sow viruses infecting cassava, maize and other cereals.

Animal virus vectors furthermore give up the foreign genes into the educated cells which make integrated into the host genome. The face of foreign genes can furthermore be enlarged using the promoters of the virus gene. The cloned genes can be used in gene therapy, pro the synthesis of valuable proteins and that. A vector based on Simian Virus 40 (SV 40) was used in the initially cloning conduct experiment relating mammalian cells in 1979. Retroviruses like murine and avian retroviruses are very helpful vectors as they are competent of infecting a generous variety of cell types and can clone generous genes. Herpes virus is a non-integrating generous sized virus (150 kb) which is a further helpful vector which can be used pro face of generous intact genes.

Artificial DNA (YAC and MAC) vectors

YACs or Yeast Artificial Chromosomes are used as vectors to clone genetic material fragments of more than 1Mb in size. These long molecules of genetic material can be cloned in mushroom by ligating them to vector sequences with the intention of allow their procreation as linear reproduction chromosomes. These long genetic material molecules can be generated and allow construction of wide-ranging libraries in microbial hosts. A ration of bring about is vacant on to create mammalian reproduction chromosomes (MACs) following the isolation of mammalian telomeres and centromere. However YACs be inflicted with a low cloning efficiency (1000 clones/microgm) genetic material as hostile to 106-107 clones/microgm genetic material pro cosmids) and furthermore it is trying to recover generous amount of wholesome slot in genetic material from party clones.

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