Selenium in biology
Selenium in Biology
Selenium (pronounced /sɪˈliːniəm/, from the Ancient Greek σελήνη (selḗnē) meaning "Moon") is a chemical element with the symbol Se and atomic number 34. It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurs in its elemental state or as pure ore compounds in the Earth's crust.
Role in Biology
Selenium is an essential micronutrient for animals and some plants. In biology, it is found in the amino acids selenocysteine and selenomethionine. In humans, selenium is a trace element nutrient that functions as a cofactor for reduction of antioxidant enzymes, such as glutathione peroxidases and certain forms of thioredoxin reductase found in animals and some plants.
Health Effects
Selenium has a role in the functioning of the immune system and thyroid gland. It may provide protection against certain heart diseases and can improve blood flow and reduce oxidative stress. However, excessive levels of selenium can lead to selenosis, a condition characterized by hair loss, nail brittleness, and neurological abnormalities such as numbness and other odd sensations.
Dietary Sources
Dietary sources of selenium include nuts, cereals, meat, mushrooms, fish, and eggs. Selenium content in food often depends on the selenium content of the soil where the food was grown.
Related Terms
- Selenoprotein: Proteins that contain selenium in the form of an amino acid, selenocysteine.
- Selenosis: A type of poisoning that results from excessive levels of selenium.
- Selenocysteine: An amino acid that contains selenium.
- Selenomethionine: A naturally occurring amino acid in which selenium substitutes for the sulfur of methionine.
External links
- Medical encyclopedia article on Selenium in biology
- Wikipedia's article - Selenium in biology
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