Unformatted text preview: used as foods by larger organisms, the phosphorus enters and is concentrated in the food chain. The sulfur cycle. Sulfur makes up a small percentage of the dry weight of a cell (approximately 1 percent), but it is an important element in the formation of certain amino acids such as cystine, methionine, and glutathione. It is also used in the formation of many enzymes. Many bacteria have an important place in the sulfur cycle in the soil. Sulfate-reducing bacteria grow in mud and anaerobic water environments, where they reduce sulfur-containing amino acids to hydrogen sulfide (H 2 S). Hydrogen sulfide accumulates in the mud of a swamp and gives the environment an odor of rotten eggs....
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- Fall '08
- Phosphorus, Biogeochemical cycle, Calcium phosphate, 1 percent