What is genetic engineering?
Genetic engineering is the deliberate transfer of a specific gene from one organism into the DNA of another, giving the receiver a new characteristic. The result is recombinant DNA — DNA that combines genetic material from two different sources. An organism that receives a foreign gene is called a transgenic or genetically modified organism (GMO), and it can then pass the new gene to its own offspring.
The main steps
The process uses special tools. Restriction enzymes cut DNA at specific sequences, acting like molecular scissors, while DNA ligase joins pieces of DNA together. A plasmid (a small circular DNA from bacteria) is often used as a vector to carry the gene into a host cell such as a bacterium.
- The desired gene is cut out with a restriction enzyme.
- A plasmid is cut open with the same enzyme.
- The gene is joined into the plasmid using DNA ligase, forming recombinant DNA.
- The plasmid is inserted into a bacterium, which then multiplies and expresses the gene.
Example
Human insulin is made by inserting the human insulin gene into a plasmid, then into the bacterium Escherichia coli. The bacteria multiply rapidly and produce large amounts of pure human insulin for people with diabetes.
Uses and concerns
Genetic engineering is used to make medicines (insulin, growth hormone, vaccines), pest-resistant crops and organisms that clean up pollution. However, there are ethical and safety concerns about releasing GMOs into the environment, their possible effects on wild species, and the long-term impact on human health, so this technology must be used responsibly and under strict regulation.
Key idea
Tools: restriction enzyme (cuts), DNA ligase (joins), plasmid (vector). Product: recombinant DNA. Classic example: bacteria making human insulin.
Remember
Use the same restriction enzyme to cut both the gene and the plasmid so their ends match and can be joined by ligase.