Issues Relating To Genetic Manipulation Flashcards
describe pyrosequencing
- It involves synthesising a single strand of DNA complementary to the strand to be sequenced one base at a time, whilst detecting by light emission which base was added at each step
1. Long length of DNA to be sequenced is mechanically cut into fragments of 300-800 base pairs using a nebuliser
2. These lengths are then degraded into single stranded DNA, these are the template DNA and they are immobilised
3. A sequencing primer is added and the DNA is then incubated with the enzyme DNA polymerase, ATP sulfurylase, luciferase, apyrase and the substrates adenosine 5 phosphosulfate and luciferin. Only one of the four possible activated nucleotides ATP, TPP, CTP and GTP is added at any one time and any light generated is detected
4. One activated nucleotide such as TTP (thymine triphosphate) is incorporated into a complementary strand of DNA using the strand to be sequenced as a template
5. As this happens two extra phosphoryls are released as pyrophosphate
6. In the presence of APS the enzyme ATP sylurylase converts the pyrophosphate to ATP
7. In the presence of this ATP the enzyme luciferase converts luciferin to oxylucifern
8. This conversion generates visible light which can be detected by a camera, the amount of light generated is proportional to the amount of ATP available and therefore indicates how many of the same type of activated nucleotide were incorporated adjacently into the complementary DNA strand
microorganisms
benefits
- make human insulin to treat all diabetics and human growth hormone to treat children with pituitary dwarfism
hazards
- microorganism could escape into the wild and transfer marker genes from antibiotic resistance to other bacteria
- also modified so they cannot synthesise an essential nutrient out of the lab so cannot live out of the lab
plants
Benefits
- were genetically modified to produce the toxin normally produced by a bacterium
- pesticide to treat insects, inserted into crop plants the GM plants produced the toxin and there is no need to spray it thereofre dont contaminate other organisms
hazards
- toxic to monarch butterflies
- do not take nectar from tobacco plants or maize plants in the wild, they feed on milkweed, despite many thousands of hectares of land planted with Bt crops the butterfly has continued to thrive
soya beans
benefits
- resistant to a herbicide were produced so that weed competing with the soya beans could be killed with the herbicide
hazards
- possible risks incldue the potential for the gene for herbicide resistance to pass into weeds producing super weeds - hasnt happened yet
golden rice
Benefits
- 500,000 children go blind and some of them die through lack of beta carotene, the precurosr to vitamin A
- genetically modified to contain a gene from daffodils so that beta carotene would be present in the rice grains, as the rice is the staple food in this region this seemed a great solution to a problem
Hazards
- some people were concerned that farmers would have to buy the seed every year but the company that developed this rice has offered free licences to farmers so they can keep and replant rice seeds
plantains
Benefits
- a local biotechnology company in Kenya is producing plantains that are nutritionally enhanced to contain more zinc, in areas where people eat very littel meat, they may be deficient in zinc
- important enzyme cofactor and essential for regulating insulin secretion
Hazards
- people fear eating food that contains foreign DNA and worry that the inserted genes will somehow be expressed in us, however all the food we eat contains genes and we digest the DNA with specific enzymes, nucleases and nucleotidases
crop plants resistant to pests
Benefits
- biotechnology company is producing crops that are resistant to pests so that farmers do not have to use pesticides
- good for farmers - 2000 people every year in Africa die through exposure to pesticides while applying them
Hazards
- concenrs that farmers might not want GM seed and would not have the choice to buy non-GM seed
- but many farmers see the benefit
pathogens
Benefits
- viruses genetically modified to have no virulence can be used ot make vaccines as they still have the anitgens on their surfaces, this reduces the chance of a vaccine making the recipient ill
- modified viruses can also be used as vectors in gene therapy
Hazards
- there have been some problems with the use of viruses of gene therpay as the allel may be inserted into the genome in a way that increases the risk of cancer
mice
Benefits
- millions of GM mice have been bred for medical research and used to develop therpaies for breast and prostate cancer, other types of mice have had certain genes knocked out so that reseachers can find out the function of those genes
Hazards
- some people object to the use of animals for medical and pharmaceutical testing - UK has strict rules
pharmacuetical proteins
Benefits
- genes fro humans pharmaceutical proteins can be inserted into goats or sheep and the human protein they express into their milk is harvested, transgenic mammals were used because this protein is too large for a bacterial cell to synthesise
Hazards
- concerns for the welfare of the GM sheep and goats, however these animals are valuable and likely to be well looked after
silk
Benefits
- silk is one of the strongest materials known
- spiders are impossible to farm but genes for spider silk have been inserted into goats
- these GM goats produce spider silk protein in their milk
- silk can be used for cables, sutures artifical ligaments and bullet proof vests
Hazards
- concerns were raised about the welfare of the GM goats, however these animals are valuable and likely to be well looked after and not to be eaten
