What is a GMO?

• GMO stands for genetically modified organism.
• Genetically modified (GM) organisms are organisms that have had their genomes changed in a way that does not happen naturally.
• By changing an organism’s genome we can change its characteristics.
• Any organism could be genetically modified, but laws restrict the creation of genetically modified humans, and the production and distribution of other GMOs is tightly regulated.
• Common examples of GMOs are GM crops used in agriculture and GM model organisms used in medical research.

A scientist with a GM plant. Image credit: Wellcome Images

How do we make GMOs?

• To create a GMO, we change specific characteristics by using lab techniques to delete or alter particular sections of DNA.
• We can also change an organism’s characteristics by introducing new pieces of DNA into their genomes. This could be:
  • DNA taken from the same species
  • DNA taken from a different species
  • DNA made synthetically in the lab.
• The process of creating GMOs is called genetic modification or genetic engineering.
• There are several techniques that can be used to modify a genome:
  • 'Agrobacterium-mediated' genetic modification is a technique used to introduce new DNA into a plant genome using a modified microbe.
  • 'Gene targeting' is a technique used to introduce new DNA into selected regions of a genome through a process called homologous recombination.
  • 'Genome editing' is a technique used to change selected regions of a genome using enzymes designed to cut specific DNA sequences.

Why do we make GMOs?

• GMOs are generally made for medical, environmental, or commercial reasons.
  • GM white mushrooms have had a gene that normally causes them to go brown altered so it no longer functions. These mushrooms take longer to go brown, prolonging their shelf-life.
  • GM bacteria have been developed that have had a gene for insulin added to their genome. These bacteria produce large quantities of insulin as they grow, which is then extracted and used by people with diabetes to control their blood sugar levels.
  •  The Acer1 gene is thought to be involved in skin diseases like psoriasis. GM mice have been made where the Acer1 gene no longer functions to study what it normally does. These mice have hair loss and are less able to control heat and water loss from their skin.

Photos comparing a normal mouse (left) with a mouse with the Acer1 gene mutated (right). The modified mouse has less hair than the normal mouse. Image credit: Liakath‑Ali et al. 2016; doi: 10.1002/path.4737 CC BY 4.0

What is not a GMO? 

• The genomes of organisms change naturally over time, for example:
  • when organisms mate, offspring get bits of DNA from both parents
  • mutations arise as a result of mistakes when DNA is copied
  • environmental factors like UV radiation can create changes in DNA.
• These changes to the DNA are not ‘genetic modifications’ as they happen naturally.