Once an mrna is produced, its message can be decoded on ribosomes. the ribosome is composed of two subunits: the subunit, which catalyzes the formation of the peptide bonds that link the amino acids together into a polypeptide chain, and the subunit, which matches the trnas to the codons of the mrna.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.