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As with the chemical antioxidants, cells are protected against oxidative stress by an interacting network of antioxidant enzymes. This detoxification pathway is the result of multiple enzymes, with superoxide dismutases catalysing the first step and then catalases and various peroxidases removing hydrogen peroxide.
As with antioxidant metabolites, the contributions of these enzymes to antioxidant defenses can be hard to separate from one another, but the generation of transgenic mice lacking just one antioxidant enzyme can be informative. Here, its cofactor is oxidised by one molecule of hydrogen peroxide and then regenerated by transferring the bound oxygen to a second molecule of substrate.
Plants, such as Arabidopsis thalianahave a particularly great diversity of isoforms. In its active state, thioredoxin acts as an efficient reducing agent, scavenging reactive oxygen species and maintaining other proteins in their reduced state.
There are at least four different glutathione peroxidase isozymes in animals. Surprisingly, glutathione peroxidase 1 is dispensable, as mice lacking this enzyme have normal lifespans,  but they are hypersensitive to induced oxidative stress. PathologyFree-radical theoryand Oxidative stress Oxidative stress is thought to contribute to the development of a wide range of diseases including Alzheimer's disease  Parkinson's disease the pathologies caused by diabetes  rheumatoid arthritis and neurodegeneration in motor neuron diseases.
Here, low density lipoprotein LDL oxidation appears to trigger the process of atherogenesiswhich results in atherosclerosisand finally cardiovascular disease. Several antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase etc.
It has been proposed that polymorphisms in these enzymes are associated with DNA damage and subsequently the individual's risk of cancer susceptibility.
This effect may involve a reduction in oxidative stress.
Exposure to oxygen and sunlight are the two main factors in the oxidation of food, so food is preserved by keeping in the dark and sealing it in containers or even coating it in wax, as with cucumbers.
However, as oxygen is also important for plant respirationstoring plant materials in anaerobic conditions produces unpleasant flavors and unappealing colors.
Antioxidants are an especially important class of preservatives as, unlike bacterial or fungal spoilage, oxidation reactions still occur relatively rapidly in frozen or refrigerated food. Thus, these foods are rarely preserved by drying; instead, they are preserved by smokingsalting or fermenting.
Even less fatty foods such as fruits are sprayed with sulfurous antioxidants prior to air drying. Oxidation is often catalyzed by metals, which is why fats such as butter should never be wrapped in aluminium foil or kept in metal containers.
Some fatty foods such as olive oil are partially protected from oxidation by their natural content of antioxidants, but remain sensitive to photooxidation.
Industrial uses[ edit ] Substituted phenols and derivatives of phenylenediamine are common antioxidants used to inhibit gum formation in gasoline petrol. Antioxidants are frequently added to industrial products. A common use is as stabilizers in fuels and lubricants to prevent oxidation, and in gasolines to prevent the polymerization that leads to the formation of engine-fouling residues.
They can be protected by antiozonants. Solid polymer products start to crack on exposed surfaces as the material degrades and the chains break. The mode of cracking varies between oxygen and ozone attack, the former causing a "crazy paving" effect, while ozone attack produces deeper cracks aligned at right angles to the tensile strain in the product.
Oxidation and UV degradation are also frequently linked, mainly because UV radiation creates free radicals by bond breakage.Purpose: Discovering and studying new bacteria can lead to new innovations and possible cures for existing or future diseases.
The investigation of bacteria can also help incubate ourselves or act quickly in response to an invasive strain. The commercial food industry has a great need in identifying Salmonella to prevent disease in consumers. Micro Student Paper.
Here is a good Example of an Unknown Lab Report in Microbiology. Example of Unknown Lab Report, Microbiology. By CPR Memphis at August 22, | am purposes, results, and order the tests where done for the Gram positive bacteria using the Unknown tube.
Table II and Flowchart II list all . Gmail is email that's intuitive, efficient, and useful. 15 GB of storage, less spam, and mobile access. The Unknown is negative to ureaCatalaseTo determine the ability of micro organism to detect presence of catalaseHydrogen PeroxideBubbling.
The bacteria detect enzymes amylase.
Amylase is the enzymes that chopped up the Hydrogen Peroxide to water and tranceformingnlp.comesTo determine the ability of bacteria to convert NO3 to NO2Nitrate . The Vaccinia virus (VACV) is a large, complex poxvirus with a genome of approximately kb.
As the basis of the live smallpox vaccine, it is also the most well-characterised poxvirus. Download-Theses Mercredi 10 juin