Biochemistry Option: Section B8 Nucleic acids

The nucleic acids section of the biochemistry option now has personal significance for me. Towards the end of last year, I was diagnosed as having type 2 diabetes. This came as a bit of a shock to me. I was not overweight and have a relatively healthy BMI of 23.6. However, after a bit of digging round into my family’s history I found out that on my father’s side of the family, his brother (my uncle), his mother (my grandmother) and her sister (my great grandmother) all had type 2 diabetes. There is a strong genetic link with type 2 diabetes so this made sense.

The hospital staff have been fantastic and I have been put on a programme to control my blood sugar levels. This has involved injecting insulin and taking Metformin tablets. Luckily, I no longer need to inject the insulin as the tablets seems to have stabilised things.

What has this got to do with chemistry I hear you ask. Well, the link is insulin. Section B8, Nucleic acids of the chemistry guide talks about ‘Genetically modified organisms have genetic material that has been altered by genetic engineering techniques, involving transferring DNA between species.’

The production of insulin is carried out in this way. Insulin was only discovered in 1921 and before this, people with diabetes had rather shortened life expectancies. Once it was discovered it was produced from the pancreas of dead cattle and given to people – but this wasn’t prefect and some people would have an allergic reaction to it.

Insulin is a protein and human insulin consists of two chains of amino acids (chain A and chain B) comprising of 21 and 30 amino acids respectively. They are joined together by two disulphide bridges.

Cow insulin differs from human insulin by 3 amino acids whilst pig insulin differs by only one amino acid – hence the reason for some people having a reaction to it.

Then in 1978 there was a break through by the medical firm Eli Lily. They produced biosynthetic insulin, sold under the brand name ‘Humulin’. The amazing thing about it was that it was produced by E. Coli bacteria. The human DNA for insulin had been spliced into the bacterial DNA. The gene was switch on and insulin was produced.

This is often a scaled down explanation of the process but it was the first large scale example of genetic engineering.

The following YouTube clip also nicely explains the genetic engineering process:

Do you have any examples of genetic engineering that you share with your classes? What are they? I would love to hear about them so please feel free to leave a comment below:

In writing this blog I used the following website to obtain some information:

The History of a Wonderful Thing We Call Insulin

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