Vector (molecular biology)

Vector (molecular biology)

Diagram of the pBR322 plasmid, a commonly used cloning vector.

In molecular biology, a vector is a DNA molecule used as a vehicle to artificially carry foreign genetic material into another cell, where it can be replicated and/or expressed. A vector containing foreign DNA is termed a recombinant DNA molecule. The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes.

Types of Vectors

Plasmids

Plasmids are small, circular, double-stranded DNA molecules that are distinct from a cell's chromosomal DNA. They are commonly used as vectors in genetic engineering because they can replicate independently of the chromosomal DNA. Plasmids are often used to clone DNA fragments in bacterial cells. The pBR322 plasmid, depicted in the image, is one of the first widely used cloning vectors.

Viral Vectors

Viral vectors are tools commonly used by molecular biologists to deliver genetic material into cells. This process can be performed inside a living organism (in vivo) or in cell culture (in vitro). Viruses have evolved specialized molecular mechanisms to efficiently transport their genomes inside the cells they infect. This makes them attractive tools for gene therapy and vaccination.

Cosmids

Cosmids are hybrid plasmid-bacteriophage vectors that can carry larger DNA fragments than standard plasmids. They are used to clone large DNA fragments (up to 45 kb) and are useful in genomic library construction.

Artificial Chromosomes

Artificial chromosomes, such as bacterial artificial chromosomes (BACs) and yeast artificial chromosomes (YACs), are used to clone very large DNA fragments. BACs can carry inserts of 100-300 kb, while YACs can carry inserts of up to 1 Mb. These vectors are used in genome mapping and sequencing projects.

Applications

Vectors are essential tools in biotechnology and molecular biology. They are used in a variety of applications, including:

• Gene cloning
• Gene expression
• Gene therapy
• Vaccine development
• Protein production

Related pages

• Recombinant DNA
• Genetic engineering
• Gene therapy
• Plasmid
• Gene cloning