Genetically Modified Organisms
Laura Armstrong & Joe Wolfensohn
Teachers
Recall Questions
This topic requires prior knowledge of recombinant DNA techniques. You can test your knowledge on these below.
What is recombinant DNA?
DNA that has been formed by combining DNA from two different sources.
What is a vector in genetic engineering?
A carrier used to transfer genetic material into a host organism (e.g. plasmid or virus).
What is the role of DNA ligase in genetic engineering?
It joins DNA fragments by forming phosphodiester bonds.
Topic Explainer Video
Check out this JoeDoesBiology video that explains genetically modified organisms or read the full notes below. Once you've gone through the whole note, try out the practice questions!
What Are Genetically Modified Organisms?
- A genetically modified organism (GMO) is one that has had its genome altered using recombinant DNA technology.
- This usually involves inserting a gene from another species to give the organism a desired characteristic.
- Can be used in bacteria, plants, animals, and even humans (e.g. gene therapy).
Examples of GMOs
1. GM Bacteria (e.g. E. coli)
- Inserted with human genes to produce useful proteins (e.g., insulin).
- Grown in large-scale fermenters to produce proteins for medical use.
- Can produce a more pure product that doesn't need as much refinement and has less risk of allergies.
- Can produce proteins that are identical to human proteins.
2. GM Crops
- Crops modified for:
- Insect resistance (e.g. Bt maize produce a toxin that kills pests)
- Herbicide tolerance (e.g. Roundup Ready soybeans are not affected by herbicides)
- Improved nutritional content (e.g. Golden Rice with vitamin A)
3. GM Animals
- Salmon that produce more growth hormones so grow faster increase muscle mass and yield.
- Sheep that produce proteins for medical uses in milk which can then be purified and extracted.
- Mice modified to have human disease genes for research.
How GMOs Are Made (Summary)
- Isolate gene of interest (e.g. using reverse transcriptase or restriction enzymes).
- Insert gene into vector (e.g. plasmid or virus).
- Introduce vector into host organism (e.g. bacterium or plant cell).
- Select transformed organisms using marker genes.
- Grow and clone the modified organism.
Benefits of GMOs
| Category | Benefits |
|
Medical |
Large-scale production of insulin, vaccines, and enzymes; gene therapy potential |
|
Agricultural |
Higher yields, resistance to pests/disease, less pesticide use |
|
Environmental |
Reduced chemical usage; potential for climate-resilient crops |
|
Nutritional |
Crops with enhanced vitamin or protein content (e.g. Golden Rice) |
Risks & Ethical Issues
| Issue | Description |
|
Ecological impact |
Plants may be grown as monocultures and GM crops may cross-breed with wild plants, reducing biodiversity |
|
Human health |
Concerns about allergens or long-term effects of GM food (no strong evidence of harm to date) |
|
Economic |
Patents may limit access for small-scale farmers |
|
Ethical |
Animal welfare in GM animals |
Key Terms
- GMO: an organism with an artificially altered genome.
- Transgenic organism: an organism that contains genes from a different species.
No answer provided.
Exam Tip
For evaluate questions, present both sides: benefits vs concerns and make sure the benefits and concerns are relevant to the type of GMO in the question.
No answer provided.
Describe one benefit and one risk of using genetically modified crops. (2 marks)
- A benefit is that GM crops can have increased resistance to pests, reducing pesticide use.
- A risk is that they may cross-breed with wild relatives, potentially affecting biodiversity.
A protein produced by a species of bacterium is toxic to caterpillars. The gene coding for this protein was removed and transferred to a crop plant. The gene was injected into isolated cells from the crop plant. These cells were then cloned and new plants grown from the cloned cells. Explain the advantage of inserting the gene into isolated plant cells rather than directly into the cells of the whole plant (2 marks)
- Isolated cells will divide by mitosis
- all cells in the new plant / clone will produce the toxin as mitosis makes genetically identical cells
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!