A clinic once used insulin from cattle and pigs, and now uses recombinant human insulin…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A clinic once used insulin from cattle and pigs, and now uses recombinant human insulin. A vaccine clinic next door gives the hepatitis B vaccine.
- Why did the insulin from animals cause an allergy in some patients?
- Give two gains of recombinant therapeutics.
- The hepatitis B vaccine is produced from yeast. What does the yeast make?
- Why can this vaccine not cause hepatitis B?
Need a reminder? The key ideaShow
Recombinant DNA technology makes safe and effective drugs in large amounts. Human insulin has two short polypeptide chains, A and B, joined by disulphide bridges. In the body it is made as a pro-hormone, which has an extra stretch, the C peptide, that is removed when the hormone matures. In 1983 the company Eli Lilly made DNA for chain A and for chain B, put them into plasmids of E. coli, made the chains separately and joined them. One A chain and one B chain make one insulin molecule. A recombinant vaccine, such as the hepatitis B vaccine, can be made in yeast.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Insulin of a non-human animal is a foreign protein for the patient. The body of some patients reacted to it.
Step 2. (b) They can be made in large amounts, and they do not cause the unwanted immune responses of products from non-human sources.
Step 3. (c) The yeast makes the protein of the virus (the antigen) whose gene was put into it.
Step 4. (d) The vaccine has only this protein and no whole virus, so it cannot cause the disease.
Answer: (a) foreign protein; (b) large amounts and no unwanted immune reactions; (c) a protein of the virus; (d) no whole virus.
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