All About Insulin: By Naomi Cook

Naomi Cook earned her bachelors in Animal Science from Cornell University and received her masters from NYU in Science Education. Currently Naomi teaches AP Biology in Wetchester, NY. She includes concepts from both Type 1 + 2 Diabetes in her core curriculum.

If you are Diabetic or you know someone who has Diabetes, then you might know how important a role the hormone insulin is. Insulin's main purpose is to help regulate the glucose levels in the human body. Glucose levels rise in accordance to food intake, and can rise faster with the consumption of sugar or simple carbohyrdrates. Unfortunately for Type 1 Diabetics, the pancreas cells do not produce insulin, and therefore it must be injected.

Considering its importance, insulin is a relatively small and simple protein. Insulin is only made up of 51 amino acids. Genes, which are made up of your DNA and packaged in the chromosomes you inherit from your parents, contain the instructions to make proteins in your body. The gene that contains instructions for insulin protein is located on the eleventh chromosome of humans. This gene should actively produce insulin in the cells of the pancreas.

So where do we get insulin for injection? Up until 1982, insulin for Diabetics came from pigs and cows. Bovine and porcine pancreases were ground up and the insulin was purified and sold to Diabetics. This created inflammation at the site of injection, because the insulin was not compatible with the human’s immune system. In addition, inherent molecular differences between human and pig or cow insulin meant the response of the human were not as optimal as it could have been. Finally, retrieving insulin from slaughtered cows and pigs is just not the most efficient way of harvesting a protein for pharmaceutical purposes.

Since genes are made of DNA, the relatively recent advances in our knowledge of DNA have meant that we are able to produce insulin more easily. In 1982, we started using recombinant DNA technology to harvest insulin. Scientists identified and isolated the insulin producing gene on the eleventh chromosome of humans. Next, scientists turn to plasmids. Plasmids are small, circular pieces of DNA that can contain several genes and are naturally found in bacterial cells. Unlike us, bacterial cells can easily accept these plasmids, and once they have accepted the plasmid, the bacteria will produce the proteins that are coded for by the genes in the plasmid. Scientists use restriction enzymes to cut open the plasmid. Then, they can take the human insulin gene and literally paste it into the plasmid using ligase enzymes.

Through a process called transformation, bacteria can be induced to accept the plasmid into their cell. Once the plasmid is in the bacteria, that bacteria will begin producing human insulin. This insulin can then be purified and packaged for therapeutic purposes. What’s more, scientists have been able to create insulin analogs, which are slower acting and better able to regulate blood glucose levels throughout the day of the diabetic. The next time you take your insulin, say a little thank you to that bacteria (probably E. Coli) that is working so hard for you.

Considering how far we have come with producing effective insulin therapeutics cheaply and effectively over the past thirty years, let’s hope that funding for genetics research will continue and we will develop an effective treatment or cure for Diabetes.

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