1.11 Genetic Engineering/Modification Flashcards
What is genetic engineering?
The basic idea of genetic engineering is to transfer a gene from the genome of one organism to the genome of another. This gives the organism that receives the gene new and useful characteristics.
What are three examples of genetically modified organisms and why?
- Sheep: to produce drugs in their milk which we can extract and use to treat diseases
- Bacteria: to produce the human hormone insulin so we can harvest it and use it to treat diabetes
- Tomato plants: a gene that helps fish to survive in cold water has been inserted to help the plant survive at low temperatures
What is gene therapy?
Giving a person the healthy version of their faulty gene to fix the problem
What is the problem with gene therapy?
It is difficult to get it to work as they would have to replace the faulty gene in all cells in the body
What is the solution to the problem in gene therapy?
Transferring the gene at an early stage of development such as in the egg or embryo stage because as the person develops, the gene would get passed on to all of the other cells
How does genetic engineering work? (5)
1) A useful gene is isolated (cut) from an organism’s genome using enzymes. The gene is then replicated to produce lots of copies.
2) Each copy is then inserted into a vector. The vector is usually a virus or a bacterial plasmid depending on the type of organism that the gene is being transferred to.
3) The vectors are then mixed with other cells, e.g. bacteria. The idea is that the vectors (containing the desired gene) will be taken up by the cells, which will become genetically modified.
4) Most of the cells don’t take up the vector and the desired gene, so the cells that have been modified need to be identified and selected. This can be done by adding a marker gene to the vectors, along with the desired gene. The marker gene allows cells that have taken up the vectors to be identified, e.g. some marker genes cause cells to fluoresce (glow) under UV light.
5) The selected cells are then allowed to replicate - each new cell will contain the desired gene and produce the protein it codes for.
Why are plasmids good vectors to use in the genetic engineering of bacteria?
They’re separate to the main chromosomal DNA and naturally pass between bacterial cells.
How can genetic engineering be used in agriculture?
Crops can be genetically modified to be resistant to herbicides. Making crops herbicide-resistant means farmers can spray their crops to kill weeks, without affecting the crop itself. This can increase crop yield, helping us to produce more food for the growing population.
How can genetic engineering be used in medicine?
Genetically engineering bacteria to produce human insulin has helped to improve healthcare. Researchers have also managed to transfer human genes that produce useful proteins into sheep and cows, e.g. human antibodies used in therapy for illnesses like arthritis. These proteins can then be extracted from the animal, e.g. from their milk.
Why are there concerns about the genetic engineering of animals? (2)
- It can be hard to predict what effect modifying its genome will have on the organism - many genetically modified embryos don’t survive and some genetically modified animals suffer from health problems later in life.
- There may be unforeseen consequences for human health.
Why are there concerns about growing genetically modified crops? (2)
- Transplanted genes may get out into the environment. E.g. a herbicide resistance gene may be picked up by weeds, creating a new ‘superweed’ variety.
- Genetically modified crops could adversely affect food chains - or even human health. Some think that more long-term studies need to be carried out so the risks are more fully understood.
How is golden rice important in developing countries?
It contains beta carotene which protects against blindness
Give three traits that could have been altered by genetic engineering in crops
- Increased yield e.g. bigger fruit
- Increased quality e.g. better taste
- Resistant to herbicides
Steps of genetic engineering for human insulin (5)
1) Isolation the insulin gene from human DNA using restriction enzymes, forming sticky ends.
2) Use the same restriction enzymes to cut open a bacterial plasmid, forming complementary sticky ends.
3) Insert the insulin gene into the plasmid using the enzyme DNA ligase, to form a recombinant plasmid.
4) Insert the recombinant plasmid into the host bacteria.
5) Let the bacteria divide and then produce the insulin protein
Which two enzymes are used during the process of genetic engineering?
- Restriction enzymes
- DNA ligase
