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Nitrogen is an essential element that makes up about 78% of the Earth's atmosphere in its gaseous form, known as nitrogen gas (Nâ‚‚). Despite this abundance, many living organisms cannot use nitrogen directly from the air. This is because gaseous nitrogen has a very stable molecular structure, with a triple bond between the two nitrogen atoms. This makes it challenging for most organisms to break down and utilize directly.
For plants and other eukaryotes, gaseous nitrogen needs to be converted into a more accessible form. This is where the role of prokaryotes becomes crucial, as they facilitate the nitrogen cycle by converting gaseous nitrogen into compounds that can be absorbed and used by eukaryotes, promoting growth and development in ecosystems.

• Stable triple bond in nitrogen gas (Nâ‚‚)
• 78% of Earth's atmosphere
• Inaccessible in its natural form to most organisms

Eukaryotes are organisms whose cells contain a nucleus and other organelles enclosed within membranes. This group includes animals, plants, fungi, and protists. Unlike prokaryotes, eukaryotes cannot directly utilize gaseous nitrogen for their nitrogen needs due to their cellular structure and lack of specific enzymes.
To grow and reproduce, eukaryotes rely on adequate nitrogen, which is a vital component of amino acids, proteins, and nucleic acids. However, they must acquire it in a form that they can metabolize, such as ammonia or nitrates. Prokaryotes play a pivotal role in this process by transforming inaccessible gaseous nitrogen into forms that eukaryotes can absorb and use.

• Have nuclei and organelles
• Includes animals, plants, fungi, and protists
• Cannot use gaseous nitrogen directly

Prokaryotes are unicellular organisms without a nucleus or membrane-bound organelles. This group includes bacteria and archaea, some of which have the ability to fix nitrogen. Nitrogen fixation is a process that converts gaseous nitrogen (N₂) into ammonia (NH₃), a form of nitrogen that can be utilized by other organisms.
Prokaryotes that perform nitrogen fixation possess an enzyme called nitrogenase, which is capable of breaking the stable triple bond in nitrogen gas. This enzymatic action is an essential component of the nitrogen cycle, allowing the transfer of nitrogen from the atmosphere to the biosphere, supporting life by providing a usable form of nitrogen for eukaryotes.

• Do not have nuclei
• Includes bacteria and archaea
• Perform nitrogen fixation

Ammonia (NH₃) is a compound that contains nitrogen and is a crucial product of nitrogen fixation by prokaryotes. After prokaryotes convert gaseous nitrogen into ammonia, this compound can then be taken up by plants and other eukaryotes.
Ammonia is an essential nitrogen source needed for synthesizing amino acids, proteins, and other vital biological molecules. Its transformation from inert atmospheric nitrogen into a biologically available form facilitates the survival and growth of various organisms within ecosystems. This process is fundamental to maintaining the nitrogen balance in nature.

• Product of nitrogen fixation
• Contains nitrogen
• Utilizable by plants and eukaryotes