#9: nitrogen and phosphorus cycles: always recycle

nitrogen cycle

biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organisms, and back into the atmosphere

nitrogenase

metalloenzyme system that plays a critical role in biological nitrogen fixation

nitrites

hold one nitrogen atom with two oxygen atoms

nitrates

hold one nitrogen atom, bonded to three different oxygen atoms

nitrate reductase

homodimeric enzyme with three electron-transferring prosthetic groups per subunit: flavin, heme, and mo cofactor

phosphorous cycle

biogeochemical cycle that describes the transformation and translocation of phosphorus in soil, water, and living and dead organic material

litosphere

solid, outer part of earth

lithotroph

diverse group of organisms using an inorganic substrate (usually of mineral origin) to obtain reducing equivalents for use in biosynthesis