Overview
This lecture explains the process and applications of genetic engineering, focusing on how microorganisms are modified to produce human insulin for diabetics.
Introduction to Genetic Engineering
- Early diabetics used animal insulin, which had several drawbacks.
- Modern insulin for diabetics is produced by genetically engineered microorganisms like E. coli or yeast.
- Genetic engineering involves altering an organism’s DNA to produce useful substances.
Key Concepts in Genetic Engineering
- Genes are DNA segments that code for proteins needed by organisms.
- Genetic engineering transfers a gene from a donor organism to a recipient, creating a transgenic or genetically modified organism (GMO).
- GMOs can be used for large-scale protein production, such as insulin, growth hormone, or vaccines.
- GMOs can also be engineered for specific traits, like pest resistance in crops.
Steps in Producing Human Insulin via Genetic Engineering
- The human insulin gene is located on chromosome 11 at position 15.5.
- Restriction enzymes cut the insulin gene from human DNA.
- Bacterial plasmids (small circular DNA) are extracted and cut open with the same restriction enzymes, creating complementary sticky ends.
- The insulin gene is inserted into the plasmid; DNA ligase enzyme joins them.
- The recombinant plasmid is returned to the bacterial cell, making it a transgenic bacterium.
- Bacteria are grown in fermenters under optimal conditions to clone and mass-produce insulin.
- Bacteria express both their own proteins and human insulin.
- Insulin is extracted, purified, and packaged for medical use.
Key Terms & Definitions
- Genetic Engineering — manipulation or alteration of an organism’s DNA.
- Transgenic/Genetically Modified Organism (GMO) — organism with DNA from another species.
- Plasmid — small circular DNA in bacteria used in genetic engineering.
- Restriction Enzyme — enzyme that cuts DNA at specific sequences.
- Sticky Ends — overhanging DNA sequences that help join DNA fragments.
- Ligase — enzyme that joins DNA fragments together.
- Recombinant DNA — DNA formed by combining DNA from different organisms.
Action Items / Next Steps
- Review the steps of inserting a human gene into bacterial plasmids.
- Study the roles of restriction enzymes, ligase, and plasmids in genetic engineering.