RuBisCORibulose-1,5-bisphosphate carboxylase/oxygenase, commonly known by the abbreviations RuBisCo, rubisco, RuBPCase, or RuBPco, is an enzyme () involved in light-independent (or "dark") part of photosynthesis, including the carbon fixation by which atmospheric carbon dioxide is converted by plants and other photosynthetic organisms to energy-rich molecules such as glucose. It emerged approximately four billion years ago in primordial metabolism prior to the presence of oxygen on earth. It is probably the most abundant enzyme on Earth.
PyrenoidPyrenoids are sub-cellular micro-compartments found in chloroplasts of many algae, and in a single group of land plants, the hornworts. Pyrenoids are associated with the operation of a carbon-concentrating mechanism (CCM). Their main function is to act as centres of carbon dioxide (CO2) fixation, by generating and maintaining a CO2 rich environment around the photosynthetic enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Pyrenoids therefore seem to have a role analogous to that of carboxysomes in cyanobacteria.
C3 carbon fixationDISPLAYTITLE: C3 carbon fixation carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosphoglycerate through the following reaction: CO2 + H2O + RuBP → (2) 3-phosphoglycerate This reaction was first discovered by Melvin Calvin, Andrew Benson and James Bassham in 1950. C3 carbon fixation occurs in all plants as the first step of the Calvin–Benson cycle.
C4 carbon fixationcarbon fixation or the Hatch–Slack pathway is one of three known photosynthetic processes of carbon fixation in plants. It owes the names to the 1960s discovery by Marshall Davidson Hatch and Charles Roger Slack that some plants, when supplied with 14, incorporate the 14C label into four-carbon molecules first. fixation is an addition to the ancestral and more common carbon fixation. The main carboxylating enzyme in photosynthesis is called RuBisCO, which catalyses two distinct reactions using either (carboxylation) or oxygen (oxygenation) as a substrate.
Calvin cycleThe Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose. The Calvin cycle is present in all photosynthetic eukaryotes and also many photosynthetic bacteria. In plants, these reactions occur in the stroma, the fluid-filled region of a chloroplast outside the thylakoid membranes.
Crassulacean acid metabolismCrassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. In a plant using full CAM, the stomata in the leaves remain shut during the day to reduce evapotranspiration, but they open at night to collect carbon dioxide () and allow it to diffuse into the mesophyll cells.
Ribulose 1,5-bisphosphateRibulose 1,5-bisphosphate (RuBP) is an organic substance that is involved in photosynthesis, notably as the principal acceptor in plants. It is a colourless anion, a double phosphate ester of the ketopentose (ketone-containing sugar with five carbon atoms) called ribulose. Salts of RuBP can be isolated, but its crucial biological function happens in solution. RuBP occurs not only in plants but in all domains of life, including Archaea, Bacteria, and Eukarya.
Plant physiologyPlant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology (structure of plants), plant ecology (interactions with the environment), phytochemistry (biochemistry of plants), cell biology, genetics, biophysics and molecular biology. Fundamental processes such as photosynthesis, respiration, plant nutrition, plant hormone functions, tropisms, nastic movements, photoperiodism, photomorphogenesis, circadian rhythms, environmental stress physiology, seed germination, dormancy and stomata function and transpiration, both parts of plant water relations, are studied by plant physiologists.
Succulent plantIn botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word succulent comes from the Latin word sucus, meaning "juice" or "sap". Succulent plants may store water in various structures, such as leaves and stems. The water content of some succulent organs can get up to 90–95%, such as Glottiphyllum semicyllindricum and Mesembryanthemum barkleyii.
TranspirationTranspiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation. Leaf surfaces are dotted with pores called stomata (singular "stoma"), and in most plants they are more numerous on the undersides of the foliage.