Recombinant DNA technology is the process that is involved in joining the DNA of two species and then inserting it into a host organism. When this is done, new genetic combinations will be produced. The means through which the recombinant DNA is produced in the laboratory is known as molecular cloning. Polymerase Chain Reaction (PRC) is a technique in biotechnology that replicates the desired DNA fragment inserted into a plasmid. The plasmid that has been recombined is transformed into a host organism that produces a large number of copies of the recombined plasmid. The host organism used in recombinant DNA technology is bacteria, and there are reasons for using bacteria as the host of recombinant DNA.

Why bacteria are used in Recombinant DNA Technology
In the production of recombinant DNA in a large number of copies, bacteria serve as the factories for them. And the uses of bacteria as the host in recombinant DNA technology are as a result of several reasons for the recombinant protein expression service, which are;
- The cloned recombinant plasmids can be isolated promptly from bacteria. Easy laboratory processes allow plasmid DNA to be secluded via bacteria cell lysis.
- In laboratory research, bacteria cells are easy to grow and maintain and can be manipulated. The growth requirements involved with using bacteria are simple and can be supplied in a petri dish. The conditions for growth can be easily supplied inside an incubator, and foreign DNA can be tolerated inside the cell.
- Plasmids which are the extrachromosomal elements of bacteria, can be manipulated, and they can also be used as carriers of recombinant DNA in cells. To insert foreign DNA, plasmids can be isolated from bacteria and then transformed into bacteria.
- Bacteria can multiply rapidly, and this is because they are small organisms that contribute to their rapid growth than complex cell types. The rates of bacteria cell division are also high.
- Bacteria are used in recombinant DNA technology because they are free and easy to work with in small and medium-sized batches. They are also cheap to feed and have easy storage capacity. In addition, they have genetics that is well understood, and the tools and protocols for working on them are cheap, simple, and quick to use.

There are several bacteria used in the recombinant DNA technology in the laboratory process, but one that is widely used out of the bacteria is the E coli. The widely used of these bacteria, among others, is due to several reasons;
- Many E Coli bacteria strains are safe to handle once reasonable hygiene is maintained.
- The genome of E Coli has an in-depth study and is comparatively simple. The genes it carries are only 4,400. Moreover, it remains haploid throughout the lifetime. As a result, protein engineering becomes easy with E Coli as a single gene is there to be masked by site-directed mutagenesis.
- With the use of E Coli in the e coli protein expression service, the preparation of competent cells, which is the cells that can uptake foreign DNA, and the transformation of recombinant molecules becomes very easy.
- E Coli has a high growth rate and replicates swiftly within 20 minutes. As a result, it becomes easy to obtain the log phase from the mid-way to maximum density.
How recombinant DNA works
When the host cell expresses protein from the recombinant genes, recombinant DNA gets into action. However, a significant amount of recombinant protein may not be produced by the host unless there is the addition of expression factors. And protein expression depends upon the gene being surrounded by a collection of signals that provide instructions to the gene by the cell for its transcription and translation.
These signals are the promoter, the ribosome binding site, and the terminator. These signals are contained in the expression vectors in which the foreign DNA is inserted. In using e coli bacteria for protein expression services, these signals are that of E Coli signals as it is unlikely that it will understand the signals of human promoters and terminators.

However, problems can be encountered in the protein expression service if the gene contains introns of signals that act as terminators to a bacterial host. And when this happens, it results in premature termination, and the recombinant protein may not be processed, folded, or degraded correctly as it should. The production of recombinant proteins in eukaryotic systems generally occurs in yeast and filamentous fungi. Using animal cells is always difficult because many of them need a solid support surface, unlike bacteria, which have complex growth needs. However, eukaryotic cells will be used when some proteins become too complex to be produced in a bacterium,
The role of bacteria in genetic engineering recombinant DNA technology is in the artificial recombinant of DNA from two organisms. The human insulin gene will be inserted into the bacteria plasmid, and the recombinant plasmid can then be used for the transformation of bacteria, which produces the insulin protein.
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