BioTech
factories." Briefly, the gene for human insulin was inserted into bacterial DNA, the result was called recombinant DNA insulin, which replaced the usage of animal insulin which caused allergy.
Mainly, Insulin is a hormone that regulates blood glucose level when it increases, returning it back to its normal level. It is secreted by the β-cells in the pancreas and synthesized by very same means as any other protein. Initially, the gene coding for Insulin production in the β-cells' DNA is transcribed forming "mRNA" (Messenger Ribonucleic acid) with complementary bases to the gene. The mRNA then exits the nucleus and is attached to the 80s Ribosomes in the cytoplasm to be translated by "t-RNA" to form the primary structure of the polypeptide "Insulin". This polypeptide then enters the "Golgi Apparatus" in the cell for chemical modification and internal processing to formulate the "Insulin Hormone.” Afterwards, it is secreted by the cell into the blood stream. Some people are born with a mutation in the gene, that codes for Insulin production, which disables their cells from producing insulin on their own (as in the case of Leonard Thompson). Fortunately, scientists have found a way to manipulate bacterial DNA and insert the insulin gene in it for the bacteria to produce it.
The process of manufacturing genetically engineered Insulin is a bit complex but as technology developed, it has become easier to implement. Firstly, a β-cell is isolated from the pancreas and centrifuged to obtain an m-RNA that is complementary to the Insulin Gene. The mRNA is then added to a petri dish with some free Nucleotides and an enzyme called "Reverse Transcriptase" which forms a complementary DNA (c-DNA) to the m-RNA. Straight after that, an alkali is added to dissolve the mRNA, leaving the c-DNA free. Nucleotides are added again to the Mixture along with another enzyme "DNA polymerase" to formulate the Insulin Gene. Now that the Insulin gene is obtained, it’s added to a vector plasmid of a bacterium but there are a few steps needed prior that.
Primarily, "Non-Coding Fragments" are added to both ends of the gene. Actually, these are fragments whose sequences of nucleotides will not be read during transcription of protein (Insulin) synthesis. A specific restriction endonuclease enzyme (ECOR-I) is then added to cut through the non-coding fragments forming sticky-ends. Now the insulin gene is read and the next step is to prepare its vector. The Vector will be a bacterial plasmid as bacteria divide quickly and produce a large amount of insulin when placed in a fermenter .To prepare it, the plasmid will be extracted from the bacterium and added to a petri dish with the same specific restriction endonuclease enzyme (ECOR-I) to cut through it making another complementary pair of sticky ends. Now that both the Insulin gene and the vector are ready, they are both transferred into a petri dish along with Ligase enzyme which is added to combine both together forming the recombinant DNA .
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