Knowra Biological carbon fixation Biological carbon fixation Biological carbon fixation is the incorporation of inorganic carbon, especially carbon dioxide, into organic compounds by living organisms. It occurs through several metabolic pathways, in photosynthetic and some nonphotosynthetic organisms.
Calvin cycle : A cyclic pathway that fixes carbon dioxide into organic molecules using ATP and NADPH. It is the most widespread carbon-fixation pathway, used by plants, algae, and many bacteria.
Carbon dioxide : A colorless gas and dissolved molecule composed of one carbon atom and two oxygen atoms. It is the principal inorganic carbon substrate fixed by many organisms.
Crop yield : The amount of harvested agricultural product produced per unit of land or other input. Crop growth depends on how effectively photosynthesis fixes carbon into biomass.
Global carbon cycle : The movement of carbon among the atmosphere, oceans, land, and living organisms. Biological fixation transfers inorganic carbon into the biosphere and helps regulate atmospheric carbon dioxide.
C4 carbon fixation : A photosynthetic strategy that initially fixes carbon dioxide into four-carbon compounds before delivering it to the Calvin cycle. It concentrates carbon dioxide around Rubisco, reducing photorespiration in hot, dry conditions.
Ribulose-1,5-bisphosphate : A five-carbon sugar phosphate that accepts carbon dioxide in the Calvin cycle. Its reaction with carbon dioxide begins the Calvin cycle's main fixation step.
Photorespiration : A metabolic process initiated when Rubisco reacts with oxygen instead of carbon dioxide. It wastes energy and releases previously fixed carbon, limiting photosynthetic productivity.
Primary production : The formation of organic matter from inorganic substances by autotrophic organisms. Carbon fixation is the carbon-incorporation component of primary production.
Crassulacean acid metabolism : A photosynthetic adaptation that separates initial carbon fixation and the Calvin cycle between night and day. It lets plants take in carbon dioxide at night while limiting water loss.
Rubisco : An enzyme that catalyzes carbon dioxide attachment to ribulose-1,5-bisphosphate. It performs the defining carbon-entry reaction in the Calvin cycle.
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