Major elements, their sources and functions in bacterial cells bo of dry ment Function Carbon organic compounds Main constituent of cellular material H2O organIc Constituent of cell material and cell water: O2 Oxvgen compounds, CO2 and is electron acceptor in aerobic respiration Nitrogen NH3. NO3. organic Constituent of amino acids, nucleic acids compounds, N2 nucleotides and coenzymes H2O. organic Main constituent of organic compounds and Hvdrogen compounds, H2 cell water phosphates Constituent of nucleic acids, nucleotides, Phosphorus 3 (PO4) phospholipids, LPs, teichoic acids SO4. H2S. So, organic Constituent cvsteine. methionine Sulfur sulfur compounds glutathione. several coenzymes Potassium 1 Potassium salts Main cellular inorganic cation and cofactor for certain enzvmes Inorganic cellular cation. cofactor for certain Magnesium 0.5 Magnesium salts enzvmatic reactions Calcium Inorganic cellular cation, cofactor for certain Calcium salts enzymes and a component of endospores Component of cytochromes and certain Ir 0.2 Iron salts nonheme iron-proteins and a cofactor for some enzvmatic reactions