Selenium is generally considered a toxic element. (It is the active component of loco weed.) However, there is growing evidence that selenium is also an essential trace element. Because glutathione peroxidase activity is crucial to the protection of red blood cells against oxidative stress, a selenium deficiency can damage red blood cells. Although sulfur is in the same chemical family as selenium, it cannot be substituted. Can you explain why? [Hint: Selenium is more easily oxidized than sulfur.] Is sulfur or selenium a better scavenger for oxygen when this gas is present in trace amounts?
Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
Selenium is generally considered a toxic element. (It is the active component of loco weed.)
However, there is growing evidence that selenium is also an essential trace element. Because
glutathione peroxidase activity is crucial to the protection of red blood cells against oxidative
stress, a selenium deficiency can damage red blood cells. Although sulfur is in the same chemical
family as selenium, it cannot be substituted. Can you explain why? [Hint: Selenium is more easily
oxidized than sulfur.] Is sulfur or selenium a better scavenger for oxygen when this gas is present
in trace amounts?
The unstable molecules formed during the cell metabolism can accumulate in cells and cause cell damage. These molecules are free radicals. This damage is prevented by the free radical scavenging activity of antioxidants. The glutathione peroxidase involves the primary antioxidant defensive system. It is essential to prevent the oxidative stress caused in the red blood cells.
Selenium is chemically similar to sulphur, but this doesn't aid the replacement of selenium by sulphur. Though both the sulphur and selenium play a major role in preventing oxidative stress in red blood cells, they have different roles. The glutathione peroxidase itself is made up of selenium. Hence, it is highly dependent on it, whereas the glutathione, which acts as the co-factor of the glutathione peroxidase enzyme is made up of sulphur. The sulphur and selenium itself can act as detoxifying scavengers. The selenium reacts faster with the reactive oxygen than sulphur, and hence, the selenium is a better scavenger for oxygen.
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