Deoxyribonucleic acid, DNA for short, is a molecule that contains the instructions an organism needs to live, develop, and reproduce. These instructions are inside every cell and passed down from parents to offspring.
The DNA molecule is similar to a set of blueprints, a recipe, or a code. It contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA code is “read” by the cell-making RNAs to make proteins. Proteins are the complex molecules that do most of the work in our bodies.
Each DNA molecule consists of two twistings, paired strands. For example, one strand of the DNA molecule defines what amino acids will make proteins; these amino acids are linked together in groups of threes. The sequence of the three-letter codes along one strand (the coding strand) determines the sequence of amino acids in a protein.
Recombinant DNA, commonly referred to as rDNA, is a form of DNA created through genetic engineering. It combines two or more different sources of DNA to create a new genetic sequence. The term recombinant means that strands of DNA from various sources are added together in a chain, like adding several links together in a chain.
Recombinant DNA is created through transformation when plasmids from bacteria are altered by inserting foreign DNA. This is achieved using restriction enzymes, ligase, and gel electrophoresis. Once done, the bacterial host cell is transformed with viral vectors containing recombinant DNA. So, they begin producing whatever product is inserted into their plasmids.
How does Recombinant DNA work?
Creating recombinant DNA is simple. What is required is a host organism and a vector to carry the new DNA into that host. The first step is to isolate the DNA that contains the gene of interest. This is done by using restriction enzymes, which cut DNA at specific sequences of bases. The enzyme cuts both strands of the DNA helix.
The second step is to cut open a vector and insert the gene into it. Vectors are usually plasmids, circular DNA molecules that replicate independently from chromosomal DNA. Plasmids from bacteria such as Escherichia coli or Salmonella typhimurium are used as vectors. They can be easily manipulated and take up foreign DNA from other organisms.
The rDNA is introduced into a recipient host cell in the third step. A standard method of doing this is through bacterial transformation. In this method, bacteria are made competent for transformation by exposing them to a mild electric current or treating them with chemicals that cause temporary pores in their cell walls. Then, the recombinant plasmid is added to the bacterial cells, which take up the plasmid through their cell walls.
Finally, the recombinant host cells are allowed to grow and replicate under conditions that favor the replication of plasmids (and therefore also allow the expression of genes on a recombinant plasmid). Since these conditions usually promote chromosomal replication, this type of artificial transformation is “transfection” rather than transformation.
Various genetic elements may be added to vectors to promote transcription or translation to improve the expression of particular genes. Typically, recombinant cells are grown in culture for several generations (or until maximum yield) and harvested for further analysis. This process may be done in a protein expression service laboratory for research purposes or within a commercial environment to produce a recombinant protein.
Examples of Recombinant DNA Technology
Recombinant DNA technology plays a role in agriculture, biotechnology, and medicine. It has also made significant contributions to science. The following are some of the applications of recombinant DNA technology:
An example of recombinant DNA technology used in food production is the production of transgenic bacteria. Such bacteria help to produce food by fermenting sugar.
Insulin is produced by recombinant DNA technology. The insulin produced through this technique is a genetically modified form not found naturally in the human body. It is more effective than the one found naturally.
Transgenic plants are produced by inserting the gene of a foreign organism into the genome of the target organism. This gives rise to new traits in the target organism, such as resistance to diseases and herbicides or increased yield.
Animals are modified genetically to make them more helpful to humans. For example, cows produce more milk with lower fat content and enhanced nutritional value. Also, pigs can be made resistant to infectious diseases.
Recombinant DNA technology can produce large quantities of proteins, essential components of vaccines. These proteins can be used in place of weakened or killed versions of the disease-causing microorganisms. For example, the hepatitis B vaccine is produced using this technology. In this technique, a specific gene from the hepatitis virus is inserted into yeast cells then cultured to make a vast quantity of proteins. These proteins are then purified and used as components of vaccine preparations.
Recombinant DNA is a powerful tool, and its applications are more diverse than its early application. For example, it’s used to understand why bees are dying out and isolate dinosaur DNA. While some of its applications are controversial, there is no end to beneficial ways to employ technology. So, we can look forward to its impact in the future.