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examBoard: Pearson Edexcel
examType: IGCSE
lessonTitle: Human Insulin Production
Genetic modification (GM) is a technology that allows scientists to change an organism's DNA. This means we can give organisms new characteristics by adding genes from other species. One of the most important applications of this technology is the production of human insulin to treat diabetes.
Key Definitions:
Insulin is a hormone that helps our body control blood sugar levels. People with Type 1 diabetes can't make their own insulin and need regular injections to survive. Before genetic modification, insulin had to be extracted from the pancreases of pigs and cows, which sometimes caused allergic reactions and wasn't always enough to meet demand.
Diabetes affects over 400 million people worldwide. Type 1 diabetes requires daily insulin injections. Using genetic modification to produce human insulin has revolutionised treatment by providing a reliable, pure supply that exactly matches what the human body needs.
Scientists use bacteria (usually E. coli) as tiny factories to produce human insulin. Here's how the process works:
Scientists identify and isolate the human insulin gene from human DNA. This gene contains the instructions for making insulin.
Special enzymes called restriction enzymes act like molecular scissors to cut DNA at specific points. These are used to cut out the insulin gene and to open a bacterial plasmid (a small circular DNA molecule).
The human insulin gene is inserted into the bacterial plasmid using an enzyme called DNA ligase, which acts like glue to join DNA pieces together.
The recombinant plasmid is inserted into bacterial cells. This process is called transformation. The bacteria now contain the human insulin gene.
Scientists identify which bacteria have successfully taken up the plasmid, often using antibiotic resistance genes as markers.
The modified bacteria are grown in large fermentation tanks where they multiply rapidly and produce human insulin as they grow.
The bacteria are harvested and broken open to release the insulin they've produced. The insulin is then purified through several filtration and chemical processes.
The purified insulin is tested for quality and safety before being packaged into vials or insulin pens for medical use.
In 1982, Humulin became the first genetically engineered human insulin approved for use. Developed by Genentech and marketed by Eli Lilly, it was a revolutionary breakthrough. Before this, diabetics relied on insulin extracted from animal pancreases, which sometimes caused allergic reactions. Humulin was identical to human insulin and transformed diabetes treatment worldwide. Today, virtually all insulin is produced using genetic modification, helping millions of people manage their diabetes effectively.
Using bacteria to produce human insulin has several important benefits:
These are special proteins that cut DNA at specific sequences called restriction sites. Each restriction enzyme recognises a particular DNA sequence. For example, EcoRI cuts DNA at the sequence GAATTC. Scientists use these enzymes to cut out the insulin gene and to open the bacterial plasmid at exactly the right spot.
This enzyme works like biological glue, joining DNA fragments together by forming bonds between them. After the insulin gene and plasmid have been cut with the same restriction enzymes, they have matching "sticky ends" that can pair up. DNA ligase seals these pieces together, creating a complete recombinant plasmid.
While genetic modification has brought many benefits, it also raises some concerns:
Despite the efficiency of GM insulin production, access remains a challenge in many parts of the world. In some countries, insulin can cost up to a month's wages. The WHO estimates that half of people who need insulin can't reliably access it. This highlights that while the technology has solved the production problem, distribution and affordability remain significant challenges. Some companies are working on programs to make insulin more affordable in low-income countries.
The success of insulin production has led to many other medical applications of genetic modification:
When studying genetic modification and insulin production for your IGCSE exams, focus on these important points:
Understanding this process demonstrates how modern biotechnology applies our knowledge of DNA structure and function to solve real-world problems like diabetes treatment.
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