Cloning Vectors and Gene Libraries

A gene library is a collection of cloned DNA fragments that together represent the complete genome of an organism.

• The tumour-inducing (Ti) plasmid of Agrobacterium tumefaciens serves as an excellent vector for successfully cloning genes in plants.
• Retroviruses act as highly effective vectors for cloning genes in animals.
• Once a desired gene or DNA fragment is ligated into one of these suitable vectors, it is transferred into a specific host (bacterial, plant, or animal) where it can multiply.

• A gene library is defined as a comprehensive collection of cloned DNA fragments that perfectly represents the entire genome of an organism.
• Genomic DNA Library: This type contains both introns and exons. It is prepared from the total DNA of a cell line or tissue by performing a partial digestion using restriction enzymes that cut the DNA frequently.
• cDNA Library: This type strictly contains only exons. It is prepared to specifically represent the entire population of functioning mRNAs present within a tissue.

• The tumour-inducing (Ti) plasmid of Agrobacterium tumefaciens and retroviruses serve as highly effective vectors for cloning genes into plant and animal hosts, respectively.
• Once a desired DNA fragment is successfully ligated into a suitable vector, it is transferred into a host organism to undergo multiplication.
• A gene library is a comprehensive collection of cloned DNA fragments that completely represents the entire genome of an organism.
• Genomic libraries are prepared from total DNA and contain both introns and exons, whereas cDNA libraries represent mRNA populations and contain only exons.