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This experiment involved placing germinating seeds (bean and radish) in a hostile, artificial environment, which contained free radicals (created by hydrogen peroxide). Different vitamins (vitamin A, C and E) were used on groups of seeds to study their protective effects as antioxidants. Vitamins generally act as catalysts, combining with proteins to create metabolically active enzymes that in turn, produce hundreds of important chemical reactions in the body. Without vitamins, many of these chemical reactions would slow down, or cease. The intricate ways in which vitamins act on the body and in plants, however, are still far from clear. During the experiment, in all radish seed germination trials, vitamin A was consistently the vitamin that allowed the most seed germination, with an 89.5% of seeds germinated in total. Vitamin E allowed the 2nd most seed germination at 82%. Vitamin C was the vitamin that germinated the least amount of radish seeds. In addition, it was hydrogen peroxide that germinated the least amount of seeds with a 69% total germination. This was expected, as these groups were saturated with the most hydrogen peroxide, and therefore had the most free radicals. However, hydrogen peroxide still germinated a small number of seeds, as the free radical content was not enough to entirely prevent germination. Hydrogen peroxide consists of two hydrogen atoms, and two oxygen atoms (H2O2). As expected, the seeds used up the H2O of the hydrogen peroxide (in order to grow), leaving an oxygen atom by itself. This oxygen atom is an unstable compound, a free radical. The radical derivatives of oxygen are the most damaging free radicals in the body. They are known as reactive oxygen species and include oxygen in its triplet state (302) or singlet state (1O2), superoxide anion (O2•-), hydroxyl radical (•OH), nitric oxide (NO•), peroxynitrite (ONOO-), hypochlorous acid (HOCl), hydrogen peroxide (H2O2) alkoxy radical (LO•), and the peroxyl radical (L-•2). However, overall, the group containing solely 5ml of water, and 5ml of hydrogen peroxide (no antioxidants) allowed the most germination to occur. This was very interesting to note. In nature, there are various elements or variables that affect seed germination overall (water supply, temperature, oxygen supply, and light). Various obstacles were encountered during the first few trials of the experiment. Although these trials were not included in the final results, they were still extremely important to insure the accuracy of these final results. In the first few trials, the groups saturated with ascorbic acid did not germinate any seeds at all. In fact, mold grew in the Petri Dishes, more specifically on the filter paper. Eventually, it was concluded that the dose of vitamin C had to be adjusted. The doses that were initially used were too high: toxic. In the subsequent trials, the doses of vitamin C were logically altered to a proper dilution. It was concluded that since the recommended daily allowance (RDA) of vitamin C was close to 100mg, then the tablet of ascorbic acid (1000mg) would have to be diluted in 50ml of water. It has been shown that vitamin C is an antioxidant, however, at higher concentrations, it has been proven as a pro-oxidant, and thus, harmful. 1000 mg ascorbic acid capsule ----- 50 ml of water X mg ----------------------------------- 5 ml of water X = 100 mg of vitamin C This dilution problem did not occur with the other vitamins, as each capsule contained the liquid RDA of vitamin A and E. Despite the fact that the concentrations were altered to the RDA of vitamin C, it still germinated the least amount of seeds out of the vitamins. When exposed to air, vitamin C solution undergoes oxidation and becomes not only ineffective but also potentially harmful (oxidized vitamin C may increase the formation of free radicals). Vitamin A, and E are fat soluble vitamins, where as vitamin C is a water soluble one. The composition, structure, and size of the bean were all factors that may have influenced their germination, in comparison to the radish seeds. Despite the difference in size and type of seed, in all experimental trials, the results consistently indicated that vitamin A was the vitamin that germinated the most seeds and vitamin C the least. Vitamin E germinated an amount of seeds in between these two values. All three vitamins had been chosen because of their known antioxidant properties; to scavenge the free radicals released by the seed’s reactions with the hydrogen peroxide. However, in the overall results of the bean seed germination trials, there is a discrepancy in that the Petri dish saturated with hydrogen peroxide germinated the most with the bean seeds. As stated above, the composition, structure and size of the bean may have been a determining factor. It is possible that the hydrogen peroxide helped to dissolve the thick outer epithelial layer of bean seed, helping it germinate faster. This situation did not occur with the radish seeds, as they have a much thinner epithelial membrane. In addition, in the overall results of the bean seed germination trials, the Petri Dishes containing water did just as well as vitamin A. Again, there are many variables affecting seed germination. Antioxidants help prevent widespread cellular destruction by willingly donating electrons in order to stabilize free radicals. More importantly, antioxidants return to the surface of the cell to stabilize, rather than damage other cellular components. Oxygen, an essential element for life, can create damaging by-products during normal cellular metabolism. Antioxidants counter act these cellular by-products, called free radicals, and bind with them before they can cause damage. If left unchecked, free radicals may cause various problems, or diseases. Beta Carotene, or vitamin A, has received particular attention as a disease preventing antioxidant. Recently, many studies have noted a lower risk of cancer and cardiovascular disease among persons whose diets include a relatively large amount of vegetable and fruits. A popular explanation is that antioxidant vitamins in vegetables and fruits prevent carcinogenesis (the formation of cancer) and atherogenesis (the formation of cardiovascular disease) by interfering passively with oxidative damage to DNA and lipoproteins (involved in cardiovascular disease). However, clinical trials have shown inconsistent results with high intake of vitamin E, vitamin A, and other antioxidants.
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