Nitrogen Cycle

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Nitrogen Noun

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[ny-truh-jen]

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Nitrogen

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A chemical element essential for all living things, serving as a key component for building proteins and DNA molecules.

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Example: This diagram shows the nitrogen cycle: bacteria fix nitrogen in the soil, plants absorb it, and decomposers return it to the soil after organisms die.

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Protein Noun

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[proh-teen]

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Protein

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Complex molecules made from amino acids that perform all the essential jobs that cells must do to function properly.

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Example: This diagram shows that proteins are large molecules made by linking many smaller units, called amino acids, together into a long chain.

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DNA Noun

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[dee-en-ey]

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DNA

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Deoxyribonucleic acid is the molecule that carries an organism's genetic information and requires nitrogen for its structural composition.

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Example: This image shows that DNA is built from units called nucleotides, which contain a phosphate, a sugar, and a nitrogenous base, linking DNA to the nitrogen cycle.

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Amino Acids Noun

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[uh-mee-noh as-ids]

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Amino Acids

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The small organic molecules that serve as the fundamental building blocks for constructing all proteins in living organisms.

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Example: This diagram shows a protein breaking down into its building blocks, which are amino acids, releasing them to be recycled in the nitrogen cycle.

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Nitrate Noun

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[nahy-treyt]

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Nitrate

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A water-soluble, nitrogen-containing compound that is readily absorbed by plants and is an essential component for building proteins.

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Example: This image shows a model of a nitrate molecule, which is made of one nitrogen atom (N) and three oxygen atoms (O).

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Atmospheric Nitrogen Noun

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[at-muh-sfer-ik ny-truh-jen]

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Atmospheric Nitrogen

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The most abundant form of nitrogen (N2) in the atmosphere, which is unusable by most organisms in its gaseous state.

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Example: This diagram shows that Earth's atmosphere is mostly (78%) nitrogen gas, which is the largest reservoir of nitrogen for the nitrogen cycle.

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Nitrogen Fixation Noun

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[ny-truh-jen fik-sey-shuhn]

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Nitrogen Fixation

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The natural or industrial process of converting unusable atmospheric nitrogen gas into a usable form like ammonia or nitrate.

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Example: This image shows root nodules on a legume plant, which house special bacteria that perform nitrogen fixation by converting atmospheric nitrogen into a usable form.

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Denitrification Noun

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[dee-nahy-truh-fi-key-shuhn]

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Denitrification

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The microbial process of converting nitrates in the soil back into gaseous nitrogen, which is then released into the atmosphere.

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Example: This diagram shows denitrification as the process where bacteria convert nitrates (NO3-) in the soil back into nitrogen gas (N2), which returns to the atmosphere.

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Runoff Noun

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[ruhn-of]

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Runoff

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Water from precipitation that flows over the land surface, often carrying pollutants like nitrates into nearby water bodies.

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Example: This diagram shows how water carries nutrients from farm fertilizers, manure, and livestock waste off the land and into a river, a process called runoff.

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Algal Bloom Noun

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[al-guhl bloom]

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Algal Bloom

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A rapid and excessive growth of algae in a body of water, typically triggered by high levels of nutrients like nitrates.

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Example: Excess nutrients, like nitrogen, in water from sources like fertilizer runoff can cause a rapid, dense growth of algae called an algal bloom.