Genetic Modification: Answers

Natural insulin used to be taken from the pancreases of pigs and cattle. Nowadays it is mostly made using genetically modified bacteria. Explain why.

The insulin made using genetically modified bacteria is the human form of insulin. This means it is less likely to cause an immune reaction (rejection) by a diabetic patient compared to the pig or cow version of insulin. Taking insulin from pigs and cows has animal-rights issues and would not be suitable for vegetarians or those who do not eat pork or beef for religious reasons.

One of the aims of genetic engineering is to produce a protein as cheaply and easily as possible. To do this, the gene which triggers production of the desired protein is inserted into a host organism.

State three reasons why bacteria make good host organisms.

Bacteria make good host organisms because they reproduce at a fast rate, which means a lot of the protein can be produced in a short amount of time. They are cheap to grow and do not take up much space.

Define vector in relation to genetic engineering.

A vector is something which delivers DNA into a cell. Examples include plasmids and viruses.

Define a plasmid in relation to genetic engineering.

A plasmid is a small circular piece of DNA found in bacterial cells. It can be used as a vector in genetic engineering to introduce a gene into bacterial cells.

Describe the process by which insulin is developed using GM bacteria.

The human insulin gene is extracted from human cells using restriction enzymes. This is inserted into a plasmid using an enzyme called ligase, producing recombinant DNA. The recombinant plasmid is placed inside a bacterium which replicates (the bacterium is now transgenic because it contains DNA from another species). Each time the bacteria replicates, the human insulin gene also replicates and the insulin protein is made inside the bacterial cells. The bacteria are grown in large fermenters then the insulin protein is extracted.

Would you advise farmers in developing countries to grow GM crops? Include benefits and disadvantages in your answer.

The benefits of using genetic modified crops are that the farmer can grow crops which are larger (higher yield), more nutritious or resistant to disease. This means the farmer can make more money from his crops than he otherwise would have.

The disadvantages to the farmer are that the seeds for GM crops tend to be expensive and may be affordable for farmers in developing countries. They can also lead to a reduction in biodiversity on his farm, for example if a plant is genetically engineered to secrete an insecticide this will reduce insect populations which will affect the whole food chain.