Question

4. Explain the difference between the free-living nitrogen fixers and the symbiotic nitrogen fixers with respect to the enzyme nitrogenase.

Answer 1

Some of the bacteria and most of Cyanobacteria are free living nitrogen fixers. The site of nitrogen fixation in Cyanobacteria is heterocyst because the enzyme nitrogenase required for nitrogen fixation acts under anaerobic conditions. Nitrogenase is irreversible inactivated by oxygen.

In free living nitrogen fixer, nitrogenase can be initiated by oxygen. Nitrogenase catalyses the breaking of bond and 3 hydrogen atoms to each nitrogen atom. Microbes that fix. N2 require 16 miles of ATP to reduce each mole of nitrogen. These organisms obtain this energy by oxidizing organic molecules.