Genetically Engineered Microoranisms
The process of engineering genetically modified (transgenic) organisms involves:
- obtaining the required gene, either by cutting out the appropriate DNA fragment (using restriction endonucease) or synthesising it from isloated mRNA (using reverse transcriptase)
- using a vector (e.g. plasmid, virus, microprojectile) to deliver the gene into the host cell
- using marker genes or DNA probes to identify the transformed cells
- cloning the transformed cells
Transgenic Plants and Animals
Bacteria are genetically engineered to produce ueful proteins, such as insulin.
Plants and animals can be genetically modified either to improve their productivity or for medical use. For example, plant crops can be made pest resistant and cows can be modified to produce human growth hormone in their milk.
- Gene guns - minute pellets covered in DNA carrying the desired gene are shot through cell wall
- Soil bacterium that invades damaged plant tissue and causes tumour-like growths, desired gene can be spliced into the plasmid, which is taken up by plant after treatment of cell wall
- Electroporation - cell membrane is temporarily disrupted by a high-voltage shock
- Coat DNA in liposomes - allow the DNA to pass through phospholipid bilayer in membrane
- Viruses. Adenoviruses - respiratory dieases. Retroviruses - RNA
- Microinjection - injecting DNA directly into nucleus of fertilised egg
Gene therapy involves treating human genetic disorders (e.g. cystic fibrosis) by adding healthy genes
The Human Genome Project has produced over 3 billion bases, including those of 20,000 to 25,000 genes in the human genome. This is important information for biological and medical research.
Gene testing (screening) allows the identification of defective alleles within individuals. An example is the blood-spot test available to all babies
Gene knockouts provide information concerning gene function, for example that cystic fibrosis involves a transmembranal protein
- improving life expectancy of patients by providing more successful drug treatment
- possibility of cures for genetic traits using gene therapy
- diagnosis, prevention and management of inherited diseases caused by defective genes
- carrier testing for certain genetically inherited dieases
- personalised medicine - targets problem without side effects
- gene disruption may trigger other diseases e.g. cancer, leukemia
- 'designer babies' info from genome research may be used to produce offspring with high IQ or better looks
- individual's genomic information may come availble to insurance companies
- GEM's could escape from labs and create 'superbugs', same for crops 'superweeds'
- unfair competition between sponsored GM crops and less productive plants for farmers
- very costly - may be more economic to research other forms of treatment
- new proteins in animals and crops may cause allergic reactions