The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. ... Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.
<span>Centrosomes are made of from arrangement of two barrel-shaped clusters of microtubules, called “centrioles,” and a complex of proteins that help additional microtubules to form.</span>
