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In cyclic photophosphorylation, the high-energy electron released from P700, a pigment in a complex called photosystem I, flows in a cyclic pathway. The electron starts in photosystem I, passes from the primary electron acceptor to ferredoxin and then to plastoquinone , next to cytochrome b 6 f (a similar complex to that found in mitochondria ...
Oxygenic photosynthesis can be performed by plants and cyanobacteria; cyanobacteria are believed to be the progenitors of the photosystem-containing chloroplasts of eukaryotes. Photosynthetic bacteria that cannot produce oxygen have only one photosystem, which is similar to either PSI or PSII .
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 ...
The enzymes in the Calvin cycle are functionally equivalent to most enzymes used in other metabolic pathways such as gluconeogenesis and the pentose phosphate pathway, but the enzymes in the Calvin cycle are found in the chloroplast stroma instead of the cell cytosol, separating the reactions. They are activated in the light (which is why the ...
The leaf is the primary site of photosynthesis in plants. There are four main factors influencing photosynthesis and several corollary factors. The four main are: [113] Light irradiance and wavelength; Water absorption; Carbon dioxide concentration; Temperature. Total photosynthesis is limited by a range of environmental factors.
By discerning the percentage of photosynthesis efficiency, Segura and Quiles were able to determine the likelihood of triggering chlororespiratory pathways. [9] They noticed that the percentage of photosynthesis efficiency remained high in test subjects where: only the leaves were chilled; only the stem was chilled; only the roots were chilled [9]
The main carboxylating enzyme in C 3 photosynthesis is called RuBisCO, which catalyses two distinct reactions using either CO 2 (carboxylation) or oxygen (oxygenation) as a substrate. RuBisCO oxygenation gives rise to phosphoglycolate, which is toxic and requires the expenditure of energy to recycle through photorespiration
Transketolase connects the pentose phosphate pathway to glycolysis, feeding excess sugar phosphates into the main carbohydrate metabolic pathways in mammals. Its presence is necessary for the production of NADPH , especially in tissues actively engaged in biosyntheses, such as fatty acid synthesis by the liver and mammary glands , and for ...