In-depth understanding of gene structure and function, together with the ability to isolate, analyze, manipulate and control genes has become routine through the enormous advances made in modern gene technology or Recombinant DNA technology.

New techniques such as the use of enzymes to cut DNA (restriction endonucleases) at specific sites, detection methods for specific DNA and RNA sequences (nucleic acid hybridization), methods for preparing large amounts (multiple copies) of specific DNA fragments (DNA cloning) and for rapidly deducing the sequence of bases in DNA (DNA sequencing), as well as a revolutionary technique called Polymerase Chain Reaction (PCR) have facilitated this increased knowledge and have made possible the many practical applications now gaining importance.

DNA is first isolated from a cell and cut into fragments of a particular size using restriction endonucleases. Most foreign DNA fragments cannot replicate autonomously and must be joined (ligated) to a DNA vectormolecule that can replicate independently in animal or microbial cells.

These vectors include bacteriophage (bacterial viruses) and plasmids (small circular double-stranded DNA molecules) and are cut with the same restriction enzymes. The recombinant DNA molecule (vector + DNA fragment) is then introduced into the host cell.

Each vector may replicate many times inside the host which, if a bacterium will also replicate many times thus permitting multiple copies of a single gene to be made.

Libraries are screened using specific labelled oligonucleotide sequences (probes) that are complementary to the DNA fragment(s) of interest. The sequence of the cloned DNA is then determined. The cloned gene can then be integrated into an expression system (bacterial, yeast, fungal, insect or mammalian cell-line) under the influence of genetic control elements to yield large amounts of a specific protein (DNA makes RNA makes Protein).

Gene technology or genetic engineering allows the biologist to take a gene from one cell and insert it into another cell which may be plant, animal or microbial (bacterial or fungal), or to produce new combinations of genes.

Gene technology may be regarded as a varied industry with enormous potential benefits that include:

1.       Understanding and Characterization of genomes (Genomics) such as:
- Bacterial Genome Projects
- Yeast Genome Projects
- Human Genome Projects

2.       Diagnosis of disease:
- Inherited disorders e.g., Cystic fibrosis, Duschenne Muscular Dystrophy
- Haemophilia
- Identification of genetic markers for specific Cancers
- Bacterial diseases e.g., TB and lyme disease
- Viral infections e.g., Hepatitis B, AIDS (HIV virus)
- Parasitic infections e.g., Malaria

3.       Gene therapy

4.       Forensic Science
- DNA fingerprints used as evidence in trials

5.       Production of Recombinant pharmaceuticals:
- Insulin (for the treatment of diabetes)
- Tissue Plasminogen Activator (TPA; necessary for dissolving life-threatening blood clots after heart attack)

6.       Production of Recombinant vaccines:
- Hepatitis B Vaccines
- Foot and Mouth Disease Vaccines
- AIDS Vaccines

7.       Creation of specific mutations yielding improved end-products (proteins)

8.       Agricultural applications such as the control of insects and pests

9.       Production of specific enzymes for food, beverage, and nutraceutic applications, as well as for use in pulp and paper, textile and detergent industries