Bioengineering Application - Certain vegetables and fruits contain plant pigment
ID: 1009147 • Letter: B
Question
Bioengineering Application - Certain vegetables and fruits contain plant pigments called carotenoids that are metabolized in the body to produce Vitamin A. Lack of Vitamin A causes an estimated 250,000 to 500,000 children worldwide to become blind every year. An approach to reducing blindness and other childhood health problems resulting from this deficiency is to use genetic engineering of rice-a food staple in developing countries and economically disadvantaged regions of the world-so that rice becomes a dietary source of Vitamin A. For example, a strain known as Golden Rice has been genetically engineered so that it can produce and store carotenoids such as beta- carotene (which helps give carrots and squash their yellow-orange color). One type of Golden Rice contains approximately 30 micrograms of carotenoids (81% beta-carotene, 16% alpha-carotene, and 3% beta-cryptoxanthin) per gram of uncooked rice. A study has reported that when a person eats Golden Rice, their body metabolizes 1 microgram of Vitamin A for every 3.8 micrograms of beta-carotene they consume. It is recommended that children between 1 and 3 years of age should get 300 micrograms of Vitamin A per day. Considering only the metabolism of beta-carotene given above, how many grams of Golden Rice would a child have to eat in order to obtain this much Vitamin A? Does this seem like a reasonable amount of rice to eat in one day, if one cup of cooked rice is approximately 175 g? alpha-carotene and beta-cryptoxanthin can also be converted into Vitamin A, but when compared to beta-carotene, it takes twice as much of each of these compounds to produce one unit of Vitamin A. Considering all of the carotenoids in Golden Rice as potential sources of Vitamin A, how many grams of Golden Rice would a three-year-old child have to eat in order to obtain the recommended daily amount of Vitamin A? Exploratory Exercises-Research and Discover Some individuals are not convinced that genetically modified foods are safe to grow or to eat. What kinds of risks or uncertainties are cited by these individuals? What kinds of measures are taken by farmers and suppliers of genetically modified seeds to minimize these risks? Some people do not believe that Golden Rice is a practical, viable solution to Vitamin A deficiency around the world. Summarize the major arguments for and against production and distribution of Golden Rice.Explanation / Answer
(a) 3.8 g of -carotene gives 1.0 g of Vitamin A on metabolism. Therefore, 300 g of Vitamin A will be obtained from metabolism of
(300 g Vitamin A)*(3.8 g -carotene/1.0 g Vitamin A) = 1140 g -carotene.
Now, carotenoids contain 81% -carotenes, i.e, 0.81 g -carotene per 1.0 g carotenoids.
1140 g -carotene is contained in (1140 g -carotene)*(1.0 g carotenoids/0.81 g carotenes) = 1407.407 g carotenoids.
1 gm uncooked rice contains 30 g carotenoids.
Therefore, 1407.407 g carotenoids is contained in (1407.407 g carotenoids)*(1 gm uncooked rice/30 g carotenoids) = 46.913 gm uncooked rice 46.92 gm uncooked rice.
Hence, a child has to consume 46.92 gm Golden Rice to get 300 g of Vitamin A daily. Since 1 cup of cooked rice is about 175 gm, this amount seems to unreasonable quantity of rice to eat.
(b) For this part, we know that 1.0 g Vitamin A is produced from (3.8*2) g = 7.6 g -carotene and (3.8*2) g = 7.6 g -cryptoxanthin combined (let’s call this other carotenes; also, it is given that one unit of Vitamin A is produced from twice the amount of each of the other carotenes).
Therefore, we can say that a total of 2.0 g Vitamin A is produced from (3.8 + 7.6 + 7.6) g = 19.0 g carotenoids (since 3.8 g -carotenes produce 1.0 g Vitamin A and 7.6 g of each of the other carotenes combined produce 1.0 g Vitamin A; also all the carotenoids produce Vitamin A as per the second assumption).
Therefore, 300 g Vitamin A is obtained from (300 g Vitamin A)*(19.0 g carotenes/2.0 g Vitamin A) = 2850 g carotenoids.
Now, 1 gm uncooked rice contains 30 g carotenoids. Therefore, 2850 g carotenoids is contained in (1710 g carotenoids)*(1 gm uncooked rice/30 g carotenoids) = 95 gm uncooked rice.
Therefore, the child will have to consume 95 gm Golden Rice in order to meet the daily requirement of Vitamin A.
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