Sam Brown

What is rDNA?

Recombinant DNA, or rDNA, is the term used to describe the combination of two DNA strands that are constructed.

What is a plasmid and how is it related to rDNA?

A plasmid is a a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan.

How is rDNA created? What is rDNA technology?

    The breakthrough that made recombinant DNA technology possible was the discovery and characterization of restriction enzymes. Restriction enzymes are produced by bacteria as a defense mechanism against phages. The enzymes act like scissors, cutting up the DNA of the phage and thereby inactivating it.

Genetic engineering, also called genetic modification, is the direct manipulation of an organism's genome using biotechnology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.

      Formation of recombinant DNA requires a cloning vector, a DNA molecule that replicates within a living cell. Vectors are generally derived from plasmids or viruses, and represent relatively small segments of DNA that contain necessary genetic signals for replication, as well as additional elements for convenience in inserting foreign DNA, identifying cells that contain recombinant DNA, and, where appropriate, expressing the foreign DNA.

      Recombinant DNA is series of procedures that are used to join together DNA.segments. A rDNA molecule is constructed from segments of two or more different DNA molecules. Recombinant DNA is widely used in biotechnology, medicine and research.

    The most common application of recombinant DNA is in basic research, in which the technology is important to most current work in the biological and biomedical sciences. Recombinant DNA is used to identify, map and sequence genes, and to determine their function.

How is rDNA technology used?

DNA fingerprinting

The technique of DNA fingerprinting was developed and established by British geneticist Dr. Alec Jeffreys. Every individual organism is unique in its finger prints. Similarly every individual differs from other in his DNA pattern or design. Finger prints can be altered by surgery but there is no known procedure available to alter the DNA design of an individual. For obtaining the DNA finger prints of an individual, one should look for genes that are highly polymorphic or occur in multiple forms in different individuals.

Food Industry

The process to manufacture cheese usually relies on an enzyme called rennet, which contains chymosin. Traditionally, this substance is taken from the stomach milk-fed cows to manufacture cheese. However, recombinant DNA of chymosin has been in use since 1990, and is genetically and structurally identical to the original enzyme, but can be produced in larger quantities and a lower cost.

Pharmaceutical Industry

Diabetic patients often require injections of human insulin to help control levels of glucose, as they have lost the ability to regulate blood glucose effectively. Using rDNA to create human insulin rather than obtain it form animal sources allows their widespread use across the pharmaceutical industry.

Recombinant human growth hormone is used to support normal growth and development for patients with malfunctions in the pituitary gland. This offers a noticeable benefit, particularly when contrasted to previously used methods of obtaining the hormone from cadavers, which could pose serious negative health effects.

Medical Research

Recombinant DNA has been used in the development of the most common diagnostic techniques for HIV.

-The antibody test uses a recombinant HIV protein to measure antibodies in the body that proliferate when there is a HIV infection.

-The DNA test uses reverse transcription polymerase chain reaction (RT-PCR) to detect presence of HIV genetic material. This technique was developed using rDNA of molecules and analyzing the genome sequences.

Agricultural Industry

Some commercial crops, such as soy, maize, sorghum, canola, alfalfa and cotton, are grown with recombinant DNA that increases resistance to herbicides used in the agricultural process. Glyphosate is the herbicide known commonly as Roundup is widely used among farmers to help with weed control and recombinant genes in the agricultural crops allow them to grow without being affected by the herbicide.

Recombinant DNA ©2004 Demonstratives, Inc.


In 1975 scientists decided to voluntarily place a moratorium on research for rDNA as concerns were expressed that there was great potential for dangerous organisms to be created and introduced to the general public. The moratorium was limited to experiments that were regarded as especially risky. The public, particularly the religiously motivated, addressed this moratorium as proof that there still was consciousness in those scientists

What is a transgenic animal?

Transgenic animals are animals with one foreign gene. Most transgenic animals are mice.

What was the first transgenic animal?

The first transgenic animal was the mouse. In 1982, the creation of the first "transgenic animal" was accomplished by transferring a gene from one animal to the embryo of another--a mouse--in such a way that the gene would be expressed in the mouse and in its future offspring

How does it relate to rDNA?

It relates to rDNA because the transgenic animal is a mixture of two genes, and recombinant DNA is the combination of two strands of DNA.


Klein, K. (1995, December 1). The Transgenic Mouse retrieved from https://www.washington.edu/research/pathbreakers/1982b.html

What is Recombiant DNA? (2015, May 5). Retrieved from http://www.news-medical.net/life-sciences/What-is-Recombinant-DNA.aspx

Mcooey, B. (2000). The Basics of Recombiant DNA retrieved from http://www.rpi.edu/dept/chem-eng/Biotech-Environ/Projects00/rdna/rdna.html