how free radical can damage the cell?
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There are many ways, but free radicals can react with a cell that alters the DNA, which could possible lead to cancer.  Check out the Wiki for more information: http://en.wikipedia.org/wiki/Free_radical
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By the ionization of the cells, for one. Radiation strips electrons from atoms making up the molecular machinery of the cell; as you may realize, this can't be good. Structures lose form/lose function.
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If you have corrupted food it will corrupt your cells
903135
Short answer, they cause cancer.\n\nLong answer:\nIn chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. These unpaired electrons are usually highly reactive, so radicals are likely to take part in chemical reactions. Because they are uncharged, their reactivity is different from the reactivity of similar ions. Radicals play an important role in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes, including human physiology. For example, superoxide and nitric oxide regulate many biological processes, such as controlling vascular tone. "Radical" and "Free Radical" are frequently used interchangeably, however a radical may be trapped within a solvent cage or be otherwise bound. The first organic free radical, the triphenylmethyl radical was identified by Moses Gomberg in 1900.\n\nHistorically, the term radical has also been used for bound parts of the molecule, especially when they remain unchanged in reactions. For example, methyl alcohol was described as consisting of a methyl 'radical' and a hydroxyl 'radical'. Neither were radicals in the usual chemical sense, as they were permanently bound to each other, and had no unpaired, reactive electrons. In mass spectrometry, such radicals are observed after breaking down the substance with a hail of energetic electrons.\nFree radicals are atoms or groups of atoms with an odd (unpaired) number of electrons and can be formed when oxygen interacts with certain molecules. Once formed these highly reactive radicals can start a chain reaction, like dominoes. Their chief danger comes from the damage they can do when they react with important cellular components such as DNA, or the cell membrane. Cells may function poorly or die if this occurs. To prevent free radical damage the body has a defense system of antioxidants.\n\nAntioxidants are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. Although there are several enzyme systems within the body that scavenge free radicals, the principle micronutrient (vitamin) antioxidants are vitamin E, beta-carotene, and vitamin C. Additionally, selenium, a trace metal that is required for proper function of one of the body's antioxidant enzyme systems, is sometimes included in this category. The body cannot manufacture these micronutrients so they must be supplied in the diet.\n\nVitamin E : d-alpha tocopherol. A fat soluble vitamin present in nuts, seeds, vegetable and fish oils, whole grains (esp. wheat germ), fortified cereals, and apricots. Current recommended daily allowance (RDA) is 15 IU per day for men and 12 IU per day for women.\n\nVitamin C : Ascorbic acid is a water soluble vitamin present in citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi, and strawberries. The RDA is 60 mg per day. Intake above 2000 mg may be associated with adverse side effects in some individuals.\n\nBeta-carotene is a precursor to vitamin A (retinol) and is present in liver, egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and grains. Because beta-carotene is converted to vitamin A by the body there is no set requirement. Instead the RDA is expressed as retinol equivalents (RE), to clarify the relationship. (NOTE: Vitamin A has no antioxidant properties and can be quite toxic when taken in excess.)
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Ha! You're probably right. The sad thing is there are cures that are found in nature. Turmeric (cumin) is a spice that is native to India, and it has amazing antioxidant properties. It can revert the damage caused by free radicals in the atmosphere, and stop cells from self-destructing or overreproducing.\n\nFenugreek, Seaweed, Eclipta Alba, and Shatavari are also good.
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Without a nucleus there is more room for haemoglobin and therefore a greater oxygen-carrying capacity.\nThe consequence is that red blood cells have a short life span; they are constantly being broken down and the parts recycled (except the haem bit which is got rid of into the gut).\nSince the red blood cells have a short life span they must continually be replaced. You can see the importance of a good supply of iron in our diet.\nYou might like to ponder over the diet of new-born mammals - there is no iron in milk.
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You're pretty much spot on WRT thepoteins. Formalin also causes DNA damage by both physically breaking the DNA strands and altering the tertiary structure.
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Protein damage through sulfydryl group interactions.  Proteins within the cell are damaged and the cell cannot proliferate (dies).
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To combat free radicals\n-----------------\nIn biological systems, the normal processes of oxidation (plus a minor contribution from ionizing radiation) produce highly reactive free radicals. These can readily react with and damage other molecules. In some cases the body uses free radicals to destroy foreign or unwanted objects, such as in an infection. However, in the wrong place, the body's own cells may become damaged. Should the damage occur to DNA, the result could be cancer. Antioxidants decrease the damage done to cells by reducing oxidants before they can damage the cell.\n\nVirtually all studies of mammals have concluded that a restricted calorie diet extends the lifespan of mammals by as much as 100%. This remarkable finding suggests that food is actually more damaging than smoking. As food produces free radicals (oxidants) when metabolized, antioxidant-rich diets are thought to stave off the effects of aging significantly better than diets lacking in antioxidants. The reduced levels of free radicals, resulting from a reduction in their production by metabolism, is thought to be a major cause of the success of caloric restriction in increasing life span.\n\nFree radical damage in the mitochondria of living cells is a byproduct of oxidative phosphorylation. Superoxide radicals are generated, which can damage mitochodrial and mitochondrial membranes. Unlike DNA in the cell nucleus, mitochondrial DNA has only a few DNA-repair enzymes and the DNA is not protected by histones.\n\nMany antioxidants, however (including vitamin C and vitamin E) can't get into mitochondria for various reasons (e.g. because they are too hydrophilic to cross mitochondrial membranes or too hydrophobic to cross the cytoplasm). Melatonin is an important natural antioxidant that has been demonstrated [citation needed] to strongly protect mitochondria from damage. A group of scientists in Russia (led by V. Skulachev) have created a custom antioxidant (a Skulachev ion forms the point of the molecule and penetrates the mitochondrial membrane; the antioxidising part is attached behind it) that can enter the mitochondria and stays there due to the membrane potential gradient; preventing damage to DNA.\n\nAlthough there is little doubt that antioxidants are a necessary component for good health, there is considerable doubt as to the most beneficial antioxidant(s) and as to the optimal amount for results. A study of lung cancer patients found that those given antioxidant supplements had worse prognoses. This is believed to be due to antioxidant interference with the body's normal use of localised free radicals e.g. Nitric oxide for cell signalling. Due to the complex nature of the interactions of antioxidants with the body, it is difficult to interpret the results of many experiments designed to test such things. In vitro testing (outside the body) has shown many natural antioxidants, in specific concentration, can halt the growth of or even kill cancerous cells.\n\nFor example, recent studies are suggesting that at high levels, synthetic antioxidant vitamins such as A, E and C may prove to have pro-oxidant effects: increasing the formation of free radicals. The fact that natural antioxidants are always ingested together with a wide variety of flavonoids and other phytochemicals also likely plays a part. Many supplement manufacturers supply more expensive tablets containing these. Newer liquid nutritional supplements using plant ionic compounds are believed to be more readily absorbed in the human body.\n\nThe benefits of antioxidants were examined during the Age-Related Eye Disease Study.\n\nNutritional antioxidants\nThe following substances have shown positive antioxidant effects:\n\nVitamin A (Retinol, also synthesized by the body from beta-carotene) protects dark green, yellow and orange vegetables and fruits from solar radiation damage, and is thought to play a similar role in the human body. Carrots, squash, broccoli, sweet potatoes, tom
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Antioxidants serve to quench byproducts of cellular activity called 'radicals'.  During the normal process of metabolism products like alcohols, sugars, proteins etc., are broken down molecular to produce heat.  Some of these products have beneficial byproducts, some have undesirable by-products.  Antioxidants, which are often found in foods and vitamin products, act specifically to target some of these chemically undesirable byproducts and inhibit their ability to cause damage to the organism.  An example of one type of damage:  skin damage from cigarette smoking.  The connective tissue [collagen] reacting to chemical radicals in smoke will "cross-link" with other collagen proteins.  The result is a tightening of the connective tissue making it less flexible.  An outward presentation of this effect is that of wrinkles on the skin.\n\nThe web page below gives you a synopsis in several sentences.
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Water equalizes the pressure between the outside and the inside of the cell wall, so it doesn't become damaged.  It also is the transport medium for nutrients coming in, and waste exiting.
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Antioxidants don't work on normal oxygen atoms, but rather on oxygen radicals.  Radicals are ionized forms of atoms or molecules that have surprisingly destructive properties and can actually cause cells to die.  Oxygen as a normal bivalent molecule (it usually floats around in pairs such as O2) has enough of its electron shells filled that it has an overall charge of zero, thereby minimizing the potential for oxidation.
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Some pros\n\nCells with a cell wall are stronger \nCells can withtsand far greater degrees of positive osmotic pressure (higher concentrations of water outside of the cell).\nWhen cells die they can still serve a purpose within the organism by contributing to structural rigidity or fluid transport (e.g. xylum in plants)\n\nSome cons\nCells with cell walls are limited in size by the size of the cell wall\nIn situations of high negative osmotic pressure the cell membrane can detatch from the cell wall and is often ruptured, killing the cell\nCells with cell walls are very rarely able to move unless they have specialist attatchments like flagella
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Uric acid and glutathione are both anti-oxidants.  Neuronal death in MS (and likely Alzheimers, etc) has been linked to higher levels of damaging reactive oxygen species, and cell culture studies indicate that antioxidants can protect neurons from this damage-and some clinical studies in humans show beneficial effects (though some also show no effect).  Glutathione depletion has been linked to cases of MS, leading to the hypothesis that this lack of intrinsic antioxidant may lead to greater neuronal death due to oxidative stress.  In other studies, serum uric acid levels were found to be reduced in MS patients, leading to the same conclusion noted for glutathione.  In one study, reduced uric acid was correlated to increased peroxynitrite, a toxic reactive compound associated with oxydative stress.  Thus, some suspect that MS patients either have reduced antioxidants leading to neuronal damage, or have reduced antioxidants because of depletion by oxidating compounds generated by the disease-and because of this, a lot of current study is looking at ways to boost antioxidants to either protect against MS or to slow it's progression.
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Generally, high energy radiation causes cell deaths.  With extremely high doses, enough of your bodies cells die that you die.  With sub-fatal doses, you can still have large numbers of cells die in  your body, or sometimes the radiation will knock atoms off of molecules in your cell's nucleus, specifically in the DNA.  If this happens, than any type of mutation is possible, since DNA is highly specific.  The most common mutation will be that the cell is unable to divide, and so it will not pass on the mutation.  The second most common mutation is that the cell overproduces, which we call cancer.
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(m)\n\nEnergy in the form of electromagnetic waves or particles capable of damaging cells by removing electrons from atoms or molecules. This damage can lead to cancer or other defects.
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Vitamin A, or Retinol, is a fat-soluble antioxidant that is absorbed in the intestines.  It is then transported to the liver where it is converted to an ester form that it is stored as.  While retinol is not an active antibiotic (it does not destroy infection causing bacteria), a deficiency in retinol can increase the likelihood of infection.  This is due to the fact that the antioxidant properties of retinol aid in the function of the immune system and contribute to a strong immune response when the body is confronted with a pathogen.  \n\nAntioxidants such as retinol are extremely important to combating dangerous molecules called free-radicals.  Free-radicals are molecules that have a single unpaired electron, which makes them extremely reactive with other molecules.  This reactivity is dangerous as it can interfere with normal biological processes by reacting with molecules that are essential to the body's own chemical reactions.  This can cause severe damage when free-radicals react with essential cellular components such as DNA, RNA, proteins, and lipid bi-layers.  When these reactions occur, cells become weakened, mutations in the genetic code can occur, and immune responses become less effective against infection.  So, while vitamin A does not in itself fight infection, a lack of it can increase the risk of infection.\n\nHopefully this helps answer your question.