Genetic Modification (or Genetic Engineering)

• Genetic modification is the process of taking a gene from one species and putting the gene into another species.
• Transgenic organism is an organism that has undergone genetic modification and has had genetic material transferred from a different species.
• Genetic engineering is beneficial because it can produce organisms that have desired characteristics.
  • Genetically modified bacteria can produce large amounts of human insulin to treat diabetes.
  • Plants can be genetically modified to have desired characteristics, such as disease resistance, larger fruits or high levels of nutrition.

Important terms to know for IGCSE Biology: 

• Restriction enzymes cut DNA at specific sites. You can think of restriction enzymes as scissors that can cut DNA!
• Ligase is an enzyme that joins pieces of DNA together. Ligases are like glues that glue DNA pieces.
• Vectors are DNA molecules that carry DNA from another species into a cell. Plasmids and viruses are commonly used as vectors for genetic engineering.
• When a gene with desired characteristics is inserted into the vector, we call it a recombinant DNA. 

How Bacteria is Genetically Modified to Produce Insulin

1. The gene that is responsible for controlling the formation of insulin is cut out from human chromosome using restriction enzyme. 
2. A plasmid is isolated from a bacteria, and the plasmid is cut with the same restriction enzyme that was used to cut the human chromosome.
3. The gene that was cut out from human chromosome is inserted into the plasmid using ligase. The plasmid now contains the insulin gene.
4. The plasmid is inserted back to the bacteria. Plasmid is the vector that carries human insulin gene into bacteria.
5. When this transgenic bacteria is grown in a fermenter, it will reproduce rapidly, and a large amount of insulin will be produced.

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