Cloning Vector

A cloning vector is a short bit of DNA that may be kept in an organism for a long time and into which a foreign DNA fragment can be inserted for cloning. The cloning vector could be DNA extracted from a virus, a cell from a higher creature, or a bacterium’s plasmid. The inclusion of restriction sites, for example, allows for the easy insertion of a DNA fragment into the vector or the removal of a DNA fragment from the vector.

The vector and foreign DNA can be cut with a restriction enzyme, resulting in DNA fragments with blunt ends or overhangs known as sticky ends. Vector DNA and foreign DNA with compatible ends can then be linked together by molecular ligation. After cloning a DNA fragment into a cloning vector, it can be subcloned into another vector tailored for a more specialised application.

A cloning vector is a genome that can receive target DNA and replicate it autonomously to increase the number of copies.

In molecular biology, all regularly used cloning vectors contain crucial qualities that are required for their function, such as a good cloning site and a selectable marker. Others may have qualities that are unique to their use. E. coli is frequently used for cloning due to its accessibility and convenience. As a result, the cloning vectors utilised frequently include features required for their propagation and maintenance in E. coli, such as a functional replication origin.

Many plasmids include the ColE1 replication origin. Some vectors contain components that enable them to be maintained in organisms other than E. coli, and these vectors are referred to as shuttle vectors.

Cloning vectors come in a variety of shapes and sizes Let us understand the type of Cloning of vector:

Type of Cloning Vector:

• Plasmid: Plasmids replicate circular extrachromosomal DNA on their own. They are the most often used and standard cloning vectors. Cloning DNA inserts up to 15 kb in size is possible with most generic plasmids. The pBR322 plasmid was one of the first widely used cloning vectors. Other cloning vectors include the pUC series of plasmids, as well as a wide range of cloning plasmid vectors. Many plasmids have a large number of copies. Low-copy-number plasmids, on the other hand, may be preferable in certain situations, such as when the protein produced by the cloned gene is harmful to the cells.
• Bacteriophage: A bacteriophage is a virus that causes bacteria to become infected. Because bacteriophages destroy their host cells, the word “bacteriophage” literally means “bacteria eater.” Bacteriophages are all made up of a nucleic acid molecule encased in a protein framework.
• Cosmid: A Lambda phage cosmid is a form of hybrid plasmid that contains the cos sequence of the Lambda phage. In genetic engineering, they’re frequently utilised as cloning vectors. Cosmids are useful for constructing genomic libraries. Collins and John were the first to describe them in 1978.
• Bacterial artificial chromosome: A bacterial artificial chromosome (BAC) is a DNA molecule that has been created to clone DNA sequences in bacteria (for example, E. coli). When it comes to DNA sequencing, BACs are frequently used. BACs can include segments of an organism’s DNA ranging in size from 100,000 to 300,000 base pairs.
• Yeast artificial chromosome: Two copies of a yeast telomeric sequence (telomeres are the sequences at the ends of chromosomes), a yeast centromere, a yeast ars (an autonomously replicating region where DNA replication begins), and corresponding selectable markers make up a yeast artificial chromosome cloning vector.
• Human artificial chromosome: Vectors based on the human artificial chromosome (HAC) provide a potential technology for delivering and expressing full-length human genes of any size. HACs overcome the limitations of viral vectors, such as restricted cloning capacity, lack of copy number control, and insertional mutagenesis produced by integration into host chromosomes.
• Animal and plant viral vectors: Foreign genes have been introduced into plant and animal cells using viruses that infect plant and animal cells. Viruses are suitable vehicles for transferring foreign DNA into eukaryotic cells in culture because of their innate capacity to adsorb to cells, introduce their DNA, and multiply. In the first mammalian cell cloning experiment, a vector-based on Simian virus 40 (SV40) was utilised. To clone genes in mammals, a multitude of vectors based on various types of viruses, such as Adenoviruses and Papillomaviruses, have been utilised. Retroviral vectors are widely used to clone genes in mammalian cells at the moment. Cauliflower mosaic virus, Tobacco mosaic virus, and Gemini viruses have all been employed with limited success on plants.

There are several cloning vectors to choose from, and the vector you choose may be determined by a variety of parameters such as the size of the insert, the number of copies, and the cloning procedure. Cloning large fragments may require a more specialized cloning vector because the huge insert may not be stably maintained in a conventional cloning vector, especially for those with a high copy number.

The pUC plasmid has a lot of copies, a lot of cloning sites, a gene for ampicillin antibiotic selection, and it can be utilized for the blue-white screen.

Conclusion

Using DNA ligase to join the DNA fragments to a cloning vector. Cloning vectors are tiny, self-replicating genetic components used to reproduce genes, such as plasmids or viral genomes. Incorporation of recombinant DNA into a host organism through DNA transformation or bacteriophage infection.

A restriction enzyme can be used to cleave the vector and foreign DNA, resulting in DNA fragments with blunt ends or overhangs known as sticky ends. By molecular ligation, vector DNA and foreign DNA with compatible ends can be joined together. After cloning a DNA fragment into a cloning vector, it can be subcloned into a more specific vector.