Antioxidants
During metabolism in the body free
This is an excerpt from the paper...
During metabolism in the body free radicals are formed and are thought to damage cells (Osawa, 1994, 77). Free radicals are also caused by environmental factors, smoking, and ultraviolet radiation (Gorgos, 2002). Oxygen occurs naturally in the atmosphere as a triplet biradical (3O2) which can lose four electrons to produce superoxide (O2), the hydroxyl radical (-OH), hydrogen peroxide (H2O2), and water (H2O) (Osawa. 1994, 77). Singlet oxygen (O2) is formed from the excited states of various pigments such as chlorophyl. These free radicals react with proteins, enzymes, DNA and RNA, and the unsaturated fatty acids found in cell membranes. Lipid peroxidation in cell membranes by free radicals is associated with many diseases, particularly cancer, and causes accelerated aging. One byproduct of lipid peroxidation is malondialdehyde (MDA), which has been implicated in the cause of mutagenesis, carcinogenesis, and the aging process (76). Most living organisms have natural defense mechanisms (enzyme systems, etc.) to deal with these free radicals and prevent them from damaging cells, and recently it has been found that exogenous antioxidants can also help perform this function (Osawa, 1994, 77). Many plant materials act as antioxidants, such as oil seeds, fruits and vegetables, grains, leaves, bark, roots, herbs, and spices (77). Studies have shown that the active antioxidant ingredients in leaf waxes from Eucalyptus, whose oil is resistant to oxidativ
. . .
e retinal cells - retinal (in terrestrial species) combined with the protein opsin (Abramov and Gordon, 1994). Each individual receptor is univariant, i.e. the same electrical signal is generated for each photon of light absorbed, regardless of the wavelength of the incident light (451). Human color vision is trichromatic, being composed of the three primary colors red, green, and blue. The photosensitive cells of the retina responsible for color vision, the cones, respond to more than one color, but each has a peak absorbency: so called red cones have a peak absorbency at 570 nanometers, green cones have a peak absorbency at 535 nanometers, and blue cones have a peak absorbency at 445 nanometers (Bianco, 2002). Approximately 64 percent of the six to seven million cones in the retina are red cones, about 32 percent are green cones, and about 2 percent are blue cones, based on measured response curves (Nave, 2003). Cones are responsible for all high resolution vision, hence their high concentration around the fovea. The blue cones are unique among the cones in that they are found outside the fovea, and are more sensitive to light than the red and green cones, though not enough to overcome their vastly smaller numbers, suggest
. . .
Some common words found in the essay are:
Abramov Gordon, Beers Fletcher, DNA RNA, Abuse Alcoholism, Academy Sciences, , Alcohol Syndrome, H2O Osawa, Vision Objects, Bianco Carl, ethyl alcohol, free radicals, berkow beers, beers fletcher, fletcher 1997, berkow beers fletcher, beers fletcher 1997, color vision, abramov gordon 1994, abramov gordon, blue cones, gordon 1994, peak absorbency, osawa 1994 77, cones peak absorbency,
Approximate Word count = 2396
Approximate Pages = 10 (250 words per page)
More Essays on Antioxidants
During metabolism in the body free
|
Customer Service
to Over
32,000 Professionally Written Papers!!!
