Home Culture Shock Culture shock is feeling unsettled when one person moves from one culture to another unfamiliar one.
Short half-life corresponds to high reactivity. The one nanosecond half-life of the hydroxyl radical indicates that it is so reactive that it reacts with the first molecule it bumps into.
Ascorbate forms H2O2 on autoxidation direct combination with oxygen. Lipid peroxidation of polyunsaturated fatty acids exposed to oxygen leads to rancidity in foods. In living animal cells peroxidized membranes lose their permeability, becoming rigid, reactive and nonfunctional.
Lipid peroxidation can produce singlet oxygen, hydroperoxides and lipid epoxides. MDA is a major metabolite of arachidonic acid Aldehyde-bridge formation leads to the protein-protein cross-linking associated with lipofuscin formation. Polyunsaturated fatty acids are more vulnerable to free radical oxidation than any other macromolecules in the body — and the sensitivity to free radical damage increases exponentially with the number of double bonds.
Animal cells contain three important enzymes to deal with the superoxide and hydrogen peroxide: A dismutase is an enzyme that catalyzes the reaction of two identical molecules to produce molecules in different oxidative states.
In the absense of SOD, two superoxide ions can spontaneously dismutate to produce hydrogen peroxide and singlet oxygen. SOD catalyzes a reaction between two superoxide ions to produce hydrogen peroxide and triplet oxygen.
CAT is present in membrane-limited organelles known as peroxisomes. Glutathione is a tripeptide composed of the amino acids cysteine, glycine and glutamic acid.
Glutathione is the major antioxidant in the non-lipid portion of cells most of the cytoplasm. Reduced glutathione hydrogen donation can neutralize a hydroxyl radical: The elimination of hydrogen peroxide by glutathione can be written as the reaction: The liver, in particular, is very high in SOD.
Cellular concentration of SOD relative to metabolic activity is a very good lifespan predictor of animal species. Most mammals experience a lifetime energy expenditure ofcalories per gram, but humans have an amazingcalories per gram.
Humans have the highest levels of SOD — relative to metabolic rate — of all species studied. Oxidative damage to DNA is ten times greater in rats than in humans.This sample expository essay explores the argument against stem cell research. Arguments against stem cell research and cloning Stem cell research refers to scientific research on elements within the human body known as stem cells for the purposes of achieving medical breakthroughs/5(5).
The Importance of Stem Cell Research - Stem cell research is a topic almost everybody in the world has a viewpoint on. Many view the issue of stem cell research and stem cell therapy as morally wrong and a crime against humanity, others view the study of stem cells as the next step in modern science.
Find the best college paper examples here! For years we have been handpicking the most interesting and professionally written high school and college essay examples so that you could write a better paper. A large number of major party contenders for political office this year took antiscience positions against evolution, human-induced climate change, vaccines, stem cell research, and more.
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