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Related Concept Videos

The Nitrogen Cycle01:49

The Nitrogen Cycle

61.3K
Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of nitrogen on Earth is nitrogen gas, which cannot be used by most animals and plants. Thus, nitrogen gas must first be converted into a usable form by nitrogen-fixing bacteria before it can be cycled through other living organisms. The use of nitrogen-containing fertilizers and animal waste products in human agriculture has greatly influenced the...
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Overview of Nitrogen Metabolism01:20

Overview of Nitrogen Metabolism

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Nitrogen is a very important element for life because it is a major constituent of proteins and nucleic acids. It is a macronutrient, and in nature, it is recycled from organic compounds and stored in the form of  ammonia, ammonium ions, nitrate, nitrite, or  nitrogen gas by many metabolic processes. Many of these metabolic processes are carried out only by prokaryotes.
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
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The Sulfur Cycle01:22

The Sulfur Cycle

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Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the atmosphere as sulfur dioxide (SO2), sulfur is released by decaying organisms, weathered rocks, geothermal vents, volcanos, and burning fossil fuels. It is deposited into the ecosystem, cycled through the biotic community, and either released back into the atmosphere as gas or deposited in marine sediment for long-term storage and eventual...
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Inorganic Nitrogen Assimilation01:22

Inorganic Nitrogen Assimilation

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Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme...
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The Carbon Cycle01:14

The Carbon Cycle

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Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
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What are Biogeochemical Cycles?00:54

What are Biogeochemical Cycles?

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The most common elements in organic molecules, carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, are only available in the ecosystem in limited amounts. Therefore, these nutrients must be recycled through both biotic and abiotic components of the ecosystem, in processes generally called biogeochemical cycles.
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Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx
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Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

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The nitrogen cycle.

Lisa Y Stein1, Martin G Klotz2

  • 1Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.

Current Biology : CB
|February 10, 2016
PubMed
Summary
This summary is machine-generated.

Microorganisms drive the global nitrogen cycle, converting atmospheric dinitrogen gas into reactive nitrogen essential for life. Industrial processes now dominate nitrogen fixation, causing significant environmental damage.

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Area of Science:

  • Biogeochemistry
  • Microbiology
  • Environmental Science

Background:

  • Nitrogen is crucial for life, ranking fourth in cellular biomass and dominating Earth's atmosphere.
  • The nitrogen cycle involves the transformation of inert dinitrogen gas (N2) into reactive nitrogen compounds vital for metabolism and growth.
  • Microbial activity is the primary driver of the extant nitrogen cycle, controlling the interconversion of nitrogen species.

Purpose of the Study:

  • To elucidate the historical and current roles of microbial and abiotic processes in the nitrogen cycle.
  • To highlight the significance of microbial nitrogen fixation prior to industrialization.
  • To underscore the environmental consequences of anthropogenic nitrogen fixation.

Main Methods:

  • Review of microbial metabolic pathways involved in nitrogen transformations.
  • Analysis of the historical impact of the Haber-Bosch process on nitrogen availability.
  • Assessment of current contributions of anthropogenic sources to the global nitrogen cycle.

Main Results:

  • Microbial enzymes are central to the reductive fixation of dinitrogen and the production of nitrogen compounds.
  • Abiotic reactions played a more significant role in the primordial atmosphere compared to the extant nitrogen cycle.
  • The Haber-Bosch process, initiated in 1909, dramatically increased fixed nitrogen levels, surpassing natural contributions.

Conclusions:

  • Microbial activities are indispensable for maintaining the Earth's nitrogen cycle.
  • Anthropogenic sources of fixed nitrogen, primarily from industrial processes and fertilizers, now vastly exceed natural inputs.
  • The overabundance of reactive nitrogen due to human activities has led to severe environmental degradation.