Principles and Applications of Gene Technology

Lessons

Senior 6 · Biology

Principles and Applications of Gene Technology

5 lessons

Lesson 5 of 5

Applications of gene technology, risks and ethical concerns

35 min

From the laboratory to the farm and the clinic

Most cheese made today is curdled with chymosin made by genetically modified microorganisms rather than taken from the stomachs of calves. People with diabetes inject human insulin made by bacteria or yeast. Some children born with severe inherited disorders have been treated by changing the DNA of their own cells. The tools of the last four lessons now reach into food, medicine, farming and the law. Each use raises questions as well as hopes: about safety, about the environment, about who profits, and about which changes to living things are acceptable. This lesson surveys the applications and then gives you a way to weigh them.

Definition

Genetically modified organism (GMO): an organism whose genetic material has been altered by gene technology in a way that does not occur naturally by mating or natural recombination. A transgenic organism carries a gene from another species.

Gene therapy: treating a disease by adding, replacing, inactivating or editing genes in a patient's cells.

Somatic gene therapy changes body cells only, so the change is not inherited. Germ-line gene therapy changes eggs, sperm or early embryos, so the change would pass to future generations.

Genome editing: making a targeted change at a chosen place in the genome, most often with the CRISPR-Cas9 system.

Gene flow: the movement of alleles from one population to another, for example by pollen.

Biosafety: the rules and procedures that protect people and the environment from possible harm from GMOs.

Applications in medicine

Application	How gene technology is used
Human proteins as medicines	Genes for human insulin, growth hormone, clotting factors for haemophilia and erythropoietin are expressed in bacteria, yeast or cultured mammalian cells. The products are identical to human proteins, are free of animal diseases and can be made in any quantity.
Vaccines	The gene for a surface protein of the hepatitis B virus is expressed in yeast; the purified protein is the vaccine, so no live virus is ever used.
Diagnosis	PCR and RT-PCR detect pathogens such as HIV and tuberculosis bacteria, and genetic tests identify alleles for inherited disorders, including in carriers.
Gene therapy	A working gene is delivered by a vector, or a faulty gene is edited, in the patient's own cells.
Forensic science	DNA profiles identify individuals and test family relationships.

Gene therapy and genome editing

In ex vivo gene therapy, cells are taken out of the body, changed in the laboratory and returned. This suits blood disorders, because the stem cells in bone marrow that make all blood cells can be collected, edited and put back:

CRISPR-Cas9 comes from a bacterial defence system against viruses. The enzyme Cas9 is guided by a short RNA molecule, the guide RNA, whose sequence of about 20 bases is designed to pair with the target DNA. Cas9 cuts both DNA strands at that point. The cell then repairs the break: either by joining the ends roughly, which usually disables the gene, or by copying a template supplied by the scientists, which writes in a precise change. Emmanuelle Charpentier and Jennifer Doudna shared the 2020 Nobel Prize in Chemistry for developing it.

In 2023 regulators in the United Kingdom and the United States approved the first CRISPR-based medicine, for sickle-cell disease and β-thalassaemia. A patient's blood stem cells are edited so that they switch back on the fetal form of haemoglobin, which does not sickle, and are then returned as in Figure 1. Such treatments are a turning point, but they currently cost millions of US dollars per patient and need specialist hospitals.

Applications in agriculture and industry

Insect-resistant crops. Bt maize and Bt cotton carry a gene from the soil bacterium Bacillus thuringiensis for a Cry protein that kills the larvae of particular insect pests that eat the plant, but is harmless to mammals, which lack the gut receptors it binds to. Farmers spray less insecticide.
Herbicide-tolerant crops, such as some soya bean varieties, survive a herbicide that kills the weeds around them.
Disease-resistant crops. Papaya carrying a gene from papaya ringspot virus resists the virus, which had devastated papaya farms in Hawaii in the 1990s.
Better nutrition. Golden Rice makes β-carotene, which the body turns into vitamin A, in its grain.
Animals. A fast-growing GM salmon was the first GM animal approved as food in the United States, in 2015.
Industry. GM microorganisms make enzymes for cheese-making, washing powders and biofuels.

In Rwanda. According to the Rwanda Agriculture and Animal Resources Development Board (RAB, 2026), the Rwanda Environment Management Authority (REMA) approved confined and open field trials of living modified (genetically modified) Victoria and Shangi (Ndamira) potato varieties over a ten-year period, in partnership with the International Potato Center (CIP) and the African Agricultural Technology Foundation (AATF). At a RAB field day in Musanze on 11 June 2026, these potatoes showed strong resistance to late blight in open fields without chemical protection. RAB notes that they can only reach farmers once the regulatory process by the Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA) is completed.

Worked example 1: analysing a field trial

Illustrative data. In a one-season trial on one site, a conventional potato variety sprayed with fungicide 12 times yielded 18 tonnes per hectare (t/ha). A disease-resistant GM version of the same variety, never sprayed, yielded 22 t/ha. (a) Calculate the percentage increase in yield. (b) Give two further benefits shown by the data. (c) Explain why these results alone are not enough to recommend the GM variety.

(a) $\frac{22 - 18}{18} \times 100 = 22\%$ (2 s.f.).
(b) 12 fewer sprays per season: lower costs for fungicide and labour, less exposure of farm workers to chemicals, and less fungicide reaching soil and water.
(c) One season on one site may not represent other years, weather or soils; there are no repeats or statistics; the trial shows nothing about whether the pathogen could evolve to overcome the resistance, about food safety assessment, about seed cost, or about whether consumers and buyers will accept it. These are why regulators require trials over several seasons and sites.

Risks and ethical concerns

Area	Concerns	Responses and evidence
Environment	Pollen may carry transgenes to wild relatives (gene flow); pests may evolve resistance to Bt proteins; harm to non-target insects; loss of crop diversity if a few varieties dominate	Trials before release; buffer zones; "refuges" of non-Bt plants to slow the evolution of resistance; monitoring after release
Human health	New allergens; antibiotic resistance marker genes; unknown long-term effects	Each product is assessed before approval. The WHO states that GM foods currently on the international market have passed safety assessments and are not likely to present risks to human health
Economics and society	Patented seed may cost more and must often be bought each season; small farmers may depend on a few companies; export markets may reject GM produce	Research by public and not-for-profit bodies (as in the Rwandan potato trials, run by RAB with CIP and AATF), licensing agreements, labelling and separate supply chains
Medical ethics	Germ-line editing would affect people who cannot consent; fear of "designer babies" and of genetic discrimination; very high cost limits access to gene therapy	Most countries forbid germ-line editing for reproduction; consent, privacy and anti-discrimination laws; efforts to lower costs
Animal welfare and beliefs	Suffering of GM animals; some people believe that moving genes between species is wrong in principle	Animal research rules; respect for diverse views and the right to choose through labelling

In 2018 a scientist in China announced the birth of twin girls whose embryos he had edited with CRISPR. The work was condemned around the world as unsafe and unethical, because the edit gave no medical benefit the girls needed and the risks to them and their descendants were unknown, and he was sentenced to prison. The case is why most scientists support a firm line between somatic therapy and germ-line editing.

Worked example 2: evaluating a gene therapy

Evaluate the use of CRISPR-edited blood stem cells to treat sickle-cell disease.

Benefits. It treats the cause rather than the symptoms: patients' cells make haemoglobin that does not sickle, and many treated patients have stopped having painful crises. It uses the patient's own cells, so there is no need to find a matched donor and no rejection.
Risks. The chemotherapy needed to clear the bone marrow is toxic and can cause infertility; CRISPR could make unwanted cuts elsewhere in the genome (off-target effects); long-term effects are not yet known because the treatment is new.
Ethics and access. The edit is somatic, so it is not inherited, and adult patients can give informed consent. However, the cost of millions of dollars per patient and the need for specialist hospitals mean that, for now, few patients in the countries where the disease is commonest can receive it.
Judgement. For patients with severe disease who can get it, the benefits are likely to outweigh the risks. The main ethical problem is not the technique but fair access, so the treatment is justified, but efforts to lower its cost and improve existing care, such as early diagnosis, are equally important.

Warning

Common mistakes

"Eating GM food changes your genes." All food contains DNA, GM or not; it is digested and does not enter your genome.
"Gene therapy is inherited by the patient's children." Somatic gene therapy is not; only germ-line changes would be.
One-sided answers. "Evaluate" questions need benefits and risks, supported by evidence, and a reasoned conclusion. "GMOs are poison" and "GMOs have no risks" are both unsupported.

Amoeba Sisters: "Genetic Engineering". A review of vectors, transformation and transgenic organisms, with examples of applications including CRISPR.

✦

Practice: applications, risks and ethics

Give two advantages of producing human insulin by gene technology rather than extracting animal insulin.
Explain why the hepatitis B vaccine made in yeast cannot cause hepatitis B.
Distinguish between somatic and germ-line gene therapy, and explain why germ-line editing is more controversial.
Describe how CRISPR-Cas9 is directed to a particular gene, and what happens after it cuts the DNA.
Explain how Bt crops reduce insecticide use, and how planting a refuge of non-Bt plants slows the evolution of resistant pests.
State what RAB (2026) reported about the late-blight-resistant potato trials in Rwanda, and the step still needed before release.
In an illustrative trial, a Bt cotton crop needed 3 insecticide sprays and the conventional crop 15. Calculate the percentage reduction in sprays.
"Rwanda should allow farmers to grow GM crops." Give two arguments for and two against this view, and reach a conclusion.

Show answersHide answers

Any two: identical to human insulin, so fewer allergic reactions; no risk of animal diseases; unlimited supply; acceptable to people who avoid animal products for religious or ethical reasons.
The vaccine is only a purified viral surface protein made from one viral gene; it contains no viral genome, so it cannot reproduce or cause infection.
Somatic therapy changes body cells; it is not inherited. Germ-line therapy changes eggs, sperm or embryos; it is inherited. Germ-line editing affects future people who cannot consent, its long-term risks are unknown, and it could be misused for non-medical enhancement.
A guide RNA of about 20 bases, designed to be complementary to the target sequence, leads Cas9 to it. Cas9 cuts both strands. The cell repairs the break, either by joining the ends (often disabling the gene) or by copying a supplied template (making a precise change).
The plants make their own Cry protein, which kills the larvae that eat them, so fewer sprays are needed. In the refuge, susceptible pests survive and mate with any resistant ones, so resistance alleles stay rare instead of being strongly selected.
REMA approved confined and open field trials of GM Victoria and Shangi (Ndamira) potatoes over ten years; at a field day in Musanze on 11 June 2026 they showed strong resistance to late blight without chemical protection. Release requires completion of the regulatory process by RICA.
$\frac{15 - 3}{15} \times 100 = 80\%$ reduction.
For: less fungicide needed (as the potato trials showed) and potentially higher, more reliable yields; lower costs and health benefits for farmers. Against: seed cost and dependence on suppliers; possible gene flow, resistance in pests, and loss of export markets. Conclusion: a balanced answer, for example that GM crops should be allowed case by case, after biosafety assessment and multi-site trials, with monitoring and fair seed access.

Key points

Medicine: recombinant human proteins (insulin, growth hormone, clotting factors), vaccines, diagnosis by PCR, gene therapy and CRISPR genome editing.
Somatic gene therapy is not inherited; germ-line editing would be, and is widely forbidden.
Agriculture: insect-resistant, herbicide-tolerant, disease-resistant and nutrient-enriched crops; in Rwanda, late-blight-resistant GM potatoes are in field trials (RAB, 2026).
Concerns: gene flow, pest resistance, non-target effects, allergens, cost and dependence, consent and fair access.
Evaluate each application case by case, using evidence on benefits, risks and ethics, under biosafety regulation.

1From the laboratory to the farm and the clinic

2Applications in medicine

3Gene therapy and genome editing

4Applications in agriculture and industry

5Risks and ethical concerns

From the laboratory to the farm and the clinic

Applications in medicine

Gene therapy and genome editing

Applications in agriculture and industry

Risks and ethical concerns