Section B3g: Living and Growing - New Genes for Old

Genetic engineering and genetic modification are relatively recent terms but humans have been genetically modifying animals and plants using selective breeding for thousands of years. Genes can also change without human intervention. This is known as mutation. Debating the arguments for and against GM ingredients provides opportunities to discuss how and why decisions about science are made and the related ethical issues. These discussions can also provide the opportunity to show that there are some questions that science cannot currently answer.

Suggested activities and experiences to select from:

Research examples of different animal and plant breeds that have been produced by selective breeding; Survey foods that contain GM ingredients; Debate the arguments for and against GM ingredients.

Assessable learning outcomes:

Foundation Tier only:
Recognise features of plants and animals that might be selected for enhancement in a breeding programme.
State that genes can be transferred from one living organism to another and that this is called genetic engineering or genetic modification. Recognise features of plants and animals that might be selected for in a genetic engineering programme.

Both tiers:
Describe the process of selective breeding involving the:

• selection characteristics;
• cross breeding;
• selection of suitable offspring over many generations

Explain how selective breeding can contribute to improved agricultural yields.

Explain some potential advantages and risks of genetic engineering and selective breeding:

• advantage - production of organisms with new features;
• disadvantage - inserted genes may have unexpected harmful effects

Describe, in outline only, some examples of genetic engineering:

• Taking the genes from carrots that control beta-carotene production and putting them into rice. Humans can then convert the beta-carotene from rice into Vitamin A (solving the problem of parts of the world relying on rice but lacking in vitamin A);
• transferring resistance to herbicides, frost damage or disease to crop plants

Higher Tier only:
Explain that a selective breeding programme may reduce the gene pool leading to problems of inbreeding:

• accumulation of harmful recessive characteristics;
• reduction in variation

Describe the principles of genetic engineering:

• selection of characteristics;
• isolation of genes;
• insertion;
• replication

Discuss the moral and ethical issues involved in genetic modification weighed against the potential benefits.

Section B3h: Living and growing - More of the same

Assessable learning outcomes

Both tiers:
Describe the advantages and disadvantages associated with the commercial use of cloned plants:

• advantage: can be sure of the characteristics of the plant since all plants will be genetically identical;
• advantage: it is possible to mass produce plants that may be difficult to grow from seed;
• disadvantage: if plants become susceptible to disease or to change in environmental conditions then all plants will be affected;
• disadvantage: lack of genetic variation

Higher Tier only:
Describe plant cloning by tissue culture:

• selection for characteristics;
• large number of small pieces of tissue;
• aseptic technique;
• use of suitable growth medium and conditions

Explain why cloning plants is easier than cloning animals:

• many plant cells retain ability to differentiate unlike animal cells which usually lose this ability at an early stage

Section B6h: Beyond the Microscope - Genetic Engineering

Biotechnology is "using life to make things". Genetic engineering has the potential to alter life on Earth in a very short time span by transferring genes from one organism to another. The advantages are enormous, the long term risks high.

Suggested activities and experiences to select from:

Research the results of pilot crops planted in the UK; Research GM crops used around the world.

Assessable learning outcomes:

Foundation Tier only:

• State that genetic engineering alters the genetic code of an organism
• State that genes from one organism will work in another organism

State that there are many uses of genetic engineering such as:

• to improve crops;
• to produce medicines

State that genetic engineering involves:

• removing a gene from one organism;
• inserting it into another organism;
• the gene works in the new organism

State that many genetically engineered plants such as Soya bean, maize and cotton are grown in many countries.

Both tiers:
Recall that genetic engineering alters the genetic code of an organism by inserting genes.
Recall that the new type of organism is called a transgenic organism.

Describe the main stages in genetic engineering:

• identification of a desired gene in one organism;
• removal of gene from DNA;
• cutting open the DNA in another organism;
• inserting the new gene into the DNA;
• gene works in transgenic organism;
• transgenic organism is then cloned to produce identical copies

Describe how bacteria can be used in genetic engineering, for example, to produce human insulin:

• gene for producing human insulin cut out of human DNA;
• loops of bacterial DNA called plasmids cut open;
• insulin gene inserted into plasmid;
• transgenic bacteria cultured by cloning;
• large quantities of insulin harvested

Describe how genetic engineering can improve crops by:

• increasing yield;
• making them resistant to weed killers;
• making plants produce other chemicals such as vitamins;
• helping plants survive in poor conditions

Higher Tier only:
Describe how restriction enzymes cut open DNA and ligase enzymes rejoin DNA strands.
State that assaying techniques are used to check that the new gene has been correctly transferred.

Describe how genetic engineering improves plants by:

• making them able to grow bigger/faster;
• making them able to grow in conditions such as salty water or drought;
• making them able to resist disease/weed killers

Discuss the advantages and disadvantages of genetic engineering.