Final answer:
In the process of nitrogen fixation, 16 ATP molecules are typically utilized to fix one molecule of diatomic nitrogen (N₂). If considered per nitrogen atom, it would be 8 ATP per nitrogen atom, since one molecule of N₂ contains two nitrogen atoms.
Step-by-step explanation:
In the process of nitrogen fixation, a significant amount of ATP is utilized. Nitrogenase, the enzyme responsible for fixing atmospheric nitrogen (N₂) into ammonia (NH₃), requires a high energy input for reducing nitrogen gas. The equation representing this biochemical process is:
N₂ + 16ATP + 8e⁻ + 8H⁺ → 2NH₃ + 16ADP + 16Pi + H₂
As you can see, 16 ATP molecules are used for the fixation of one molecule of nitrogen gas. This high energy cost is necessary due to the strong triple bond of dinitrogen that needs to be broken. However, the question states 'typically', and it might be hinting at a per nitrogen basis, then half the amount, or 8 ATP are used per nitrogen atom since the equation shows 16 ATP for two nitrogen atoms (which come from one ₂ molecule).
If the question refers to the general usage for each molecule of N₂ fixed, then the answer would be 16 ATP, but if it asks per nitrogen atom, it should be considered as 8 ATP used per nitrogen atom fixed from the atmosphere.