It stands for Recombinant DNA. Before we get to the “r” part we need to understand DNA. DNA is the keeper of all the information needed to recreate an organism. All DNA is made up of a base consisting of sugar, phosphate and one nitrogen base. There are four nitrogen bases, adenine (A), thymine (T), guanine (G), and cytosine (C). The nitrogen bases are found in pairs, with A & T and G & C paired together. The sequence of the nitrogen bases can be arranged in an infinite ways, and their structure is known as the “double helix”.
The sugar used in DNA is deoxyribose. The four nitrogen bases are the same for all organisms. The sequence and number of bases is what creates diversity. DNA does not actually make the organism, it only makes proteins. The DNA is transcribed into mRNA and mRNA is translated into protein, and the protein then forms the organism. By changing the DNA sequence, the way in which the protein is formed changes. This leads to either a different protein, or an inactive protein.
Now that we know what DNA is, this is where the recombinant comes in. Recombinant DNA is the general name for taking a piece of one DNA, and and combining it with another strand of DNA. Thus, the name recombinant! By combining two or more different strands of DNA, scientists are able to create a new strand of DNA. The most common recombinant process involves combining the DNA of two different organisms. There are 3 different ways to create rDNA. They are Transformation, Phage Introduction, and Non-Bacterial Transformation.
Recombination DNA is the reslut of combining DNA sequences that normally do not occur together. The key to rDNA is the precense of short sequences in the DNA that are recognized by restriction endonucleases, enzymes that clip the double-stranded DNA. Some enzymes reslut in a blunt end, others leave an overhang that can join like a puzzle piece to another strand. This is the limitation to technology, though there are many endonucleases to choose from, the presence of the particular sequence in the gene of intrest.