Module 7 Lesson 5 - 3
Completion requirements
Lesson 5 — Genetic Engineering
Recreating the First Chimera
Read page 649
In 1973, American scientists were able to produce the first genetically engineered organism that contained foreign DNA from an unrelated species. This genetically engineered organism is called a chimera. Foreign DNA (an amphibian gene) was inserted into the circular plasmid DNA of bacteria.
Bacteria have been used in this way since 1982 to synthesize human insulin to treat diabetes. Genetically engineered bacteria have been used to produce other medicines such as human growth hormone to treat dwarfism and clotting factors to treat hemophilia.
Bioremediation is another use of genetically altered bacteria. The metabolic functions of bacteria can be enhanced through genetic engineering to allow them to clean up soils polluted with PCBs, clean up oil spills, filter air from factory smoke stacks, and remove heavy metals from water.
Watch the following animation that illustrates the process.
Self-Check
Complete these Self-Check questions.
1. How can transgenic organisms help to achieve social, economic, or environmental goals? Give one example of a transgenic bacterium, transgenic plant, and transgenic animal designed for one of these goals.
2. Give two examples of social, legal or moral issues that are associated with the development of transgenic organisms.
3. A private company has developed a transgenic carrot that secretes its own pesticide. This carrot is, therefore, resistant to the insects and worms that often damage root crops.
a. What are some of the risks and benefits that the Canadian government will consider when deciding whether to approve this plant for agricultural use?
b. If approved, what advantages will this transgenic carrot offer to farmers? What are some potential drawbacks for farmers?
1. The benefits of transgenic organisms include improving human health, cleaning up toxic spills, producing plants with more nutritional value, producing pharmaceutical products, and producing animals that could serve as organ
donors for humans.
Examples include:
• Transgenic bacteria are making pure human insulin, making medicines at lower costs, and are used to clean up oil spills.
• Transgenic plants, such as golden rice, provide higher nutritional value to feed those who are starving or deficient in certain nutrients.
• Transgenic animals, such as goats, are genetically modified to secrete a human polypeptide or other substances in their milk.
2. Social, legal, and moral issues associated with transgenic organisms involve environmental threats, health effects and social and economic issues. These concerns are summarized below:
• Environmental threats: The use of herbicide-resistant plants could encourage farmers to use higher levels of herbicides. This, in turn, could lead to build up of herbicide chemicals in water supplies and neighbouring ecosystems. As well, there is evidence that engineered genes can be transferred to wild plants and other organisms, raising concerns about the emergence of “superweeds” and “superbugs”. More generally, ecosystems involve complex and delicate balances among many different organisms. The introduction of transgenic bacteria, plants, or animals could upset these balances, with unknown results.
• Health effects: Many consumer groups argue that not enough is known about the long-term effects of consuming transgenic products, including genetically modified foods and medicines. The complex processes of gene regulation are not well understood, so it is difficult to predict potential health risks.
• Social and economic issues: Advocates of genetically modified foods argue that these foods will help to improve human health and alleviate world hunger. Their opponents argue that genetic research absorbs millions of dollars, which would be better spent directly helping people in need. In addition, many people are concerned about the growing influence of private corporations over global food production. The treatment of plants and animals as commodities to be manipulated and patented also raises questions about our relationships with – and responsibilities to – other living organisms.
3. a. Prior to approving the plant for use and for human livestock consumption, it should be demonstrated that it is safe and there are no short-term, nor long-term adverse effects resulting from its consumption. Testing on laboratory animals may not be conclusive in determining whether or not it is
b. Advantage - Larger crops. Drawbacks - increased cost of seeds
Examples include:
• Transgenic bacteria are making pure human insulin, making medicines at lower costs, and are used to clean up oil spills.
• Transgenic plants, such as golden rice, provide higher nutritional value to feed those who are starving or deficient in certain nutrients.
• Transgenic animals, such as goats, are genetically modified to secrete a human polypeptide or other substances in their milk.
2. Social, legal, and moral issues associated with transgenic organisms involve environmental threats, health effects and social and economic issues. These concerns are summarized below:
• Environmental threats: The use of herbicide-resistant plants could encourage farmers to use higher levels of herbicides. This, in turn, could lead to build up of herbicide chemicals in water supplies and neighbouring ecosystems. As well, there is evidence that engineered genes can be transferred to wild plants and other organisms, raising concerns about the emergence of “superweeds” and “superbugs”. More generally, ecosystems involve complex and delicate balances among many different organisms. The introduction of transgenic bacteria, plants, or animals could upset these balances, with unknown results.
• Health effects: Many consumer groups argue that not enough is known about the long-term effects of consuming transgenic products, including genetically modified foods and medicines. The complex processes of gene regulation are not well understood, so it is difficult to predict potential health risks.
• Social and economic issues: Advocates of genetically modified foods argue that these foods will help to improve human health and alleviate world hunger. Their opponents argue that genetic research absorbs millions of dollars, which would be better spent directly helping people in need. In addition, many people are concerned about the growing influence of private corporations over global food production. The treatment of plants and animals as commodities to be manipulated and patented also raises questions about our relationships with – and responsibilities to – other living organisms.
3. a. Prior to approving the plant for use and for human livestock consumption, it should be demonstrated that it is safe and there are no short-term, nor long-term adverse effects resulting from its consumption. Testing on laboratory animals may not be conclusive in determining whether or not it is
b. Advantage - Larger crops. Drawbacks - increased cost of seeds
Genetically Modified Organisms (GMOs)
Some genetically modified plants have much controversy surrounding them. Bt corn is a genetically modified organism (GMO) that makes up about 50% of the corn crops in Canada. Bt is a naturally occurring soil bacterium called Bacillus thuringiensis that produces a protein that acts as an insecticide. Scientists isolated this protein from Bacillus thuringiensis and inserted it into the corn DNA. The resulting transgenic Bt corn produces the Bt protein insecticide, therefore killing
pests that feed on the plant.
In 1999, a study from Cornell University showed that monarch caterpillars that fed on milkweed covered in Bt corn pollen grew more slowly and had higher mortality rates. News agencies picked up this story quickly, and many articles and reports resulted. Read the following about the risks of genetically modified foods.
Bt Corn: Is It Worth the Risk?
In 1999, a study from Cornell University showed that monarch caterpillars that fed on milkweed covered in Bt corn pollen grew more slowly and had higher mortality rates. News agencies picked up this story quickly, and many articles and reports resulted. Read the following about the risks of genetically modified foods.
Bt Corn: Is It Worth the Risk?
© Getty Images
Transgenic Organisms
Read pages 655 - 656
Genetic engineers have been able to insert foreign DNA into plants and animals. Transgenic organisms are the result of these procedures. One example of a transgenic plant is golden rice, described in figure 18.22 on page 655 of your
textbook. This figure shows the four plant and fungus genes that have been added to this rice to increase its iron and vitamin A content. Read more about transgenic plants on page 655.
Transgenic organisms other than bacteria and plants have also been developed. A few examples of these transgenic organisms are listed:
- Goats that produce spider silk in milk for pharmaceutical products
- Sheep whose milk has proteins to help treat cystic fibrosis
- Cows whose milk has an iron transport protein that is added to infant formula
- Chickens that produce human proteins in the whites of their eggs
- Mice that can be used in biological experiments
- Pigs whose organs can be donated to humans