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During C 4 photosynthesis, an evolved pathway to increase localized CO 2 concentrations under the threat of enhanced photorespiration, CO 2 is captured within mesophyll cells, fixed as oxaloacetate, converted into malate and released internally within bundle sheath cells to directly feed RuBisCO activity. [9]
Nicotinamide adenine dinucleotide phosphate, abbreviated NADP [1] [2] or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NADPH as a reducing agent ('hydrogen source').
This ratio is an important component of what is called the redox state of a cell, a measurement that reflects both the metabolic activities and the health of cells. [26] The effects of the NAD + /NADH ratio are complex, controlling the activity of several key enzymes, including glyceraldehyde 3-phosphate dehydrogenase and pyruvate dehydrogenase .
The electron transport chain of photosynthesis is often put in a diagram called the Z-scheme, because the redox diagram from P680 to P700 resembles the letter Z. [3] The final product of PSII is plastoquinol, a mobile electron carrier in the membrane. Plastoquinol transfers the electron from PSII to the proton pump, cytochrome b6f. The ultimate ...
Mitotic cell division enables sexually reproducing organisms to develop from the one-celled zygote, which itself is produced by fusion of two gametes, each having been produced by meiotic cell division. [5] [6] After growth from the zygote to the adult, cell division by mitosis allows for continual construction and repair of the organism. [7]
In enzymology, a hydrogen dehydrogenase (NADP+) (EC 1.12.1.3) is an enzyme that catalyzes the chemical reaction H 2 + NADP + ⇌ {\displaystyle \rightleftharpoons } H + + NADPH Thus, the two substrates of this enzyme are H 2 and NADP + , whereas its two products are H + and NADPH .
Photosystem II is present on the thylakoid membranes inside chloroplasts, the site of photosynthesis in green plants. [9] The structure of Photosystem II is remarkably similar to the bacterial reaction center, and it is theorized that they share a common ancestor. The core of Photosystem II consists of two subunits referred to as D1 and D2 ...
The apicoplast organelle in these organisms is believed to have come from an endosymbiotic event in which an ancestral protozoan engulfed an algal cell. [7] These apicoplasts contain plant-like FNRs that the protozoan uses to generate reduced ferredoxin , which is then used as a reductant in essential biosynthetic pathways. [ 17 ]