Crop | Herbicide tolerance | Insect resistance | Herbicide tolerance and insect resistance combined | Total |
---|---|---|---|---|
soybean | 48.4 | - | - | 48.4 |
maize | 4.3 | 11.2 | 3.8 | 19.3 |
cotton | 1.5 | 4.5 | 3.0 | 9.0 |
canola (oilseed rape) | 4.3 | - | - | 4.3 |
total | 58.5 | 15.7 | 6.8 | 81.0 |
Note: this table gives the area (in millions of hectares) given over to the cultivation of each type of GM crop: herbicide-tolerant, insect-resistant, and with both attributes combined. No other GM crops were grown on a significant scale.
In Figure 4 , three positions on the Ti plasmid are marked by letters A, B and C. Which would be the best place to insert the foreign gene?
What features of a normal Ti plasmid ( Figure 4 ) are missing from the artificial Ti plasmid (Figure 5a)?
Which of these features is essential to allow transfer and integration of the genes in the T-DNA region?
What is the purpose of the kanamycin?
What would be the advantages of modifying a plant in order to produce the Bt toxin?
Colour | Mass (μg) equivalent to activity of 1 μg of retinol (RE scale) | Mass (μg) equivalent to activity of 1 μg of retinol (RAE scale) | |
---|---|---|---|
Provitamin A carotenoids | |||
α-carotene | orange | 12 | 24 |
β-carotene | orange | 6 | 12 |
β-cryptoxanthin | orange | 12 | 24 |
Other common dietary carotenoids | |||
lutein | red | n/a | n/a |
zeaxanthin | yellow | n/a | n/a |
lycopene | red | n/a | n/a |
According to the WHO, a woman aged 25-50 should consume a recommended dietary allowance (RDA) of 800 μg Retinol Equivalents (REs) each day. If it were the sole source of retinol in her diet, what mass of β-carotene would a woman have to consume each day to meet this requirement?
What sort of diet will minimise vitamin A deficiency (VAD)?
Is β-carotene coded for by a gene?
Given that GGPP is already present in the cells of the rice endosperm, how many genes have to be introduced to allow its conversion into β-carotene?
Why do you think that Potrykus and his co-workers initially used the less effective biolistic transformation method?
What is the role of a promoter sequence?
Look again at Figure 9 and Figure 10. Assuming the enzymes are expressed and active in both cases, what intermediates from the β-carotene pathway would you expect to see produced in the rice grains from each experiment?
We predicted that Experiment 1 might produce red rice. What has happened?
The road to better nutrition is not paved with gold and, hence, agribusiness has not centred its efforts on the nutritional value of food. The work that culminated in the production of golden rice was funded by grants from the Rockefeller Foundation, the Swiss Federal Institute of Technology and the European Community Biotech Program. Like the plant varieties that made the Green Revolution so successful, the rice engineered to produce provitamin A will be freely available to the farmers who need it most. One can only hope that this application of plant genetic engineering to ameliorate human misery without regard to short-term profit will restore this technology to political acceptability.
Vitamin A deficiency causes half a million children to become partially or totally blind each year. Traditional breeding methods have been unsuccessful in producing crops containing a high vitamin A concentration, […] Golden Rice, may be a useful tool to help treat the problem of vitamin A deficiency in young children living in the tropics.