5.3 - Genetic modification Flashcards
What are restriction enzymes?
Restriction enzymes are used to isolate the required gene, leaving it with ‘sticky ends’ (a short section of unpaired bases)
A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends (plasmids are circles of DNA found inside bacterial cells)
The plasmid and the isolated gene are joined together by DNA ligase enzyme
If two pieces of DNA have matching sticky ends (because they have been cut by the same restriction enzyme), DNA ligase will link them to form a single, unbroken molecule of DNA
What are vectors?
Plasmids and viruses can act as vectors for genetic engineering
They take up pieces of DNA and then insert this recombinant DNA into other cells
Viruses transfer DNA into human cells or bacteria
Plasmids - transfer DNA into bacteria or yeast
The genetically engineered plasmid is inserted into a bacterial cell
When the bacteria reproduce the plasmids are copied as well and so a recombinant plasmid can quickly be spread as the bacteria multiply and they will then all express the gene and make the human protein
The genetically engineered bacteria can be placed in a fermenter to reproduce quickly in controlled conditions and make large quantities of the human protein
Why is insulin manufactured?
The gene for human insulin can be inserted into bacteria which then produce human insulin which can be collected and purified for medical use to treat people with diabetes
Explain the process of manufacturing insulin?
The gene that is to be inserted is located in the original organism – the gene for insulin production is located within a human chromosome
Restriction enzymes are used to isolate or ‘cut out’ the human insulin gene, leaving it with ‘sticky ends’ (a short section of unpaired bases)
A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends (plasmids are circles of DNA found inside bacterial cells)
The plasmid and the isolated human insulin gene are joined together by DNA ligase enzyme
If two pieces of DNA have matching sticky ends (because they have been cut by the same restriction enzyme), DNA ligase will link them to form a single, unbroken molecule of DNA
The genetically engineered (recombinant) plasmid is inserted into a bacterial cell
When the bacteria reproduce the plasmids are copied as well and so a recombinant plasmid can quickly be spread as the bacteria multiply and they will then all express the human insulin gene and make the human insulin protein
The genetically engineered bacteria can be placed in a fermenter to reproduce quickly in controlled conditions and make large quantities of the human protein
Why is bacteria useful for genetic engineering?
They contain the same genetic code as the organisms we are taking the genes from, meaning they can easily ‘read’ it and produce the same proteins
There are no ethical concerns over their manipulation and growth (unlike if animals were used, as they can feel pain and distress)
The presence of plasmids in bacteria, separate from the main bacterial chromosome, makes them easy to remove and manipulate to insert genes into them and then place back inside the bacterial cells
What are genetically modified plants?
Genetically modified plants are plants that have had foreign DNA inserted into their genome
This is usually done to improve food production in some way
Crops can be genetically modified (they are known as GM crops)
which plants have been genetically modified and what are their adaptions?
Crop plants, such as wheat and maize, have been genetically modified to contain a gene from a bacterium that produces a poison that kills insects, making them resistant to insect pests such as caterpillars. This can improve crop yields
Crop plants have also been genetically modified to make them resistant to certain herbicides (chemicals that kill plants), meaning that when the herbicide is sprayed on the crop it only kills weeds and does not affect the crop plant
Why are crops genetically modified?
Some crops have been genetically modified to produce additional vitamins and improved nutritional value, eg. ‘golden rice’ contains genes from another plant and a bacterium which make the rice grains produce a chemical that is turned into vitamin A in the human body, which could help prevent deficiency diseases in certain areas of the world
Some have been genetically modified to be drought-resistant (to grow better in very dry conditions). This can also improve crop yields
What are the advantages of GM crops?
Reduce use of chemicals such as herbicides and pesticides better for the environment cheaper consuming farmers
Increased yields from the crops as they are not competing with weeds for resources or suffering from pest damage
What are the disadvantages of GM crops?
Increased costs of seeds companies that make GM seeds charge more for them to cover the cost of developing them this can mean smaller poorer farmers cannot complete with larger farms
Increased dependency on certain chemicals such as the herbicides that crops are resistant often made by the same companies that produce the seed and more expensive to buy
Risk on inserted genes being transferred to wild plants by pollination which could reduce the usefulness of GM crop
Reduced Biodiversity as there are fewer plant species when herbicides have been used this can impact insects and insect fatting birds.
What does transgenic mean?
ransgenic means the transfer of genetic material from one species to a different species
If an organism contains DNA from a different species it is called a transgenic organism
Any organism that has introduced genetic material is a genetically modified organism (GMO)
