Modern Medical Laboratory Journal

Molecular cloning or simply gene cloning is an essential technique to create DNA-based experimental tools for expression in bacterial or mammalian cells. The technique involves clipping the desired DNA segment out of the surrounding DNA and copying the segment millions of times. Traditionally, molecular cloning is defined as the isolation and amplification of a specific DNA fragment. Most of these fragments are created either by digesting an existing piece of DNA with restriction enzymes.
Molecular cloning is similar to a polymerase chain reaction (PCR) in that it permits the replication of the DNA sequence. The fundamental difference between the two methods is that molecular cloning involves replication of the DNA in a living microorganism, while PCR replicates DNA in an in vitro solution, free of living cells.
7 Main Steps in Gene Cloning:

1. Isolation of DNA (Gene of Inter­est) Fragments to be Cloned
2. Insertion of Isolated DNA into the Suitable Vector to Form the Recombinant DNA
3. Introduction of the Recombinant DNA into a Suitable Organism known as Host
4. Selection of the Transformed Host Cells and Identification of the Clone Con­taining the Gene of Interest
5. Multiplication/Expression of the Introduced Gene in the Host
6. Isolation of the Multiplied Gene Copies/Protein Expressed by the Intro­duced Gene
7. Purification of the Isolated Gene Copy/Protein

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