An Overview of Recombinant DNA Technology

Recombinant DNA technology was developed when scientists understood that DNA is the genetic material and learned how to isolate, cut, and join DNA molecules. The important steps were:

- discovery of the double-helical structure of DNA;
- understanding of replication, transcription, and translation;
- development of methods to isolate and purify DNA;
- discovery of enzymes such as restriction enzymes that cut DNA and ligase that joins DNA fragments.

At the same time, scientists found that foreign DNA fragments can enter bacteria and get integrated into their genome. Stanley Cohen had the skill to introduce plasmid DNA into *E. coli* and clone it, while Herbert Boyer could cut DNA using restriction enzymes. By combining these discoveries, they created the first recombinant DNA and started rDNA technology.

In crop improvement, rDNA technology is used to produce genetically modified crops with useful traits such as:

- disease resistance,
- drought resistance,
- salinity tolerance,
- improved quality of production and value of products.

These help farmers by reducing crop loss and allowing cultivation in adverse conditions.

In therapeutics, rDNA technology is used to produce important human proteins and medicines in bacteria or other systems, such as:

- human insulin for diabetes,
- growth hormone for dwarfism,
- interferon for cancer treatment,
- plasminogen activator and urokinase to dissolve blood clots.

These products are cheaper, available in larger quantity, and avoid some problems of animal-derived products.

The chapter states that Joshua Lederberg discovered plasmids in 1952. So the correct answer is Joshua Lederberg.