Genetic engineering

Genetic engineering is also called genetic modification or GM. It involves modifying the genome of an organism by introducing a gene from another organism to result in a desired characteristic.

Genetic engineering involves these steps:

  1. selection of the desired characteristic
  2. the gene responsible for the characteristic is 'cut out' of the chromosome
  3. the gene is transferred and inserted into another organism
  4. replication of the modified organism

Plant crops have been genetically engineered to be disease resistant or to produce bigger fruits.

Current uses of genetic engineering

Type 1 diabetes is a disorder in which the body's pancreas does not produce enough insulin. The affected person cannot control their blood glucose levels.

Type 1 diabetes can be controlled by injecting insulin. The extra insulin allows the glucose to be taken up by the liver and other tissues, which results in cells receiving the glucose they need, and blood glucose levels staying normal.

Previously, insulin was extracted from the pancreas of pigs or cattle, but these do not have an identical composition to human insulin. Bacterial cells have been genetically modified - by inserting the human gene for insulin production into their plasmids - so that the bacteria produce human insulin.

Current genetically engineered crops include those that are resistant to insect attack or are herbicide resistant. This results in increased yields. Herbicide resistant crops allow them to tolerate herbicides sprayed on them, but weeds, which would otherwise compete with the crops are killed by it.

Scientists have recently added a gene to bananas - from a species of banana found in Papua New Guinea - that makes them produce beta carotene. This changes the colour of the flesh of the bananas to a golden-yellow colour. Beta carotene is needed by humans in order to make vitamin A, which is essential for good vision.

The advantage of golden bananas is that they could be grown and used to feed people in areas where vitamin A deficiency is common, so the bananas could help prevent blindness, and the death of many people.

Sheep and goats have been genetically engineered to produce chemicals in their milk that can be used to treat disease. In one example, the milk produced contains a protein needed to treat patients with cystic fibrosis.

Research is also exploring the possibility of providing tissues needed for transplants from animals that have been genetically engineered so that the tissues are not rejected by the human immune system.

In the future, researchers are hoping to use genetic engineering to be able to overcome some inherited disorders, such as cystic fibrosis and Huntington's disease amongst others.

Potential benefits and risks of genetic engineering

Benefits of genetic engineering

  • Genetic modification is a faster and more efficient way of getting the same results as selective breeding.
  • Improves crop yields or crop quality, which are particularly important in developing countries. This may help reduce hunger around the world.
  • Introduce herbicide resistance in crops, so that weeds can be controlled without harming crops.
  • Insect and pest resistance can be developed and inserted into the crop plants. The plants produce toxins, which would kill insects eating the crop.

Risks of genetic engineering

  • Transfer of the selected gene into other species. GM crops might breed with wild relatives of the crop plants.
  • Some people believe it is not ethical to interfere with nature in this way.
  • GM crop seeds are more expensive. Crop growers cannot collect seed from their plants and sow them, because they are different genetically - they must buy new seeds every year - so people in developing countries may not be able to afford them.
  • GM crops could be harmful, for example toxins from the crops have been detected in some people’s blood.
  • GM crops could cause allergic reactions in people.
  • Pollen produced by the plants could be toxic and harm insects that transfer it between plants.