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In oxygenic photosynthesis, the first electron donor is water, creating oxygen (O 2) as a by-product. In anoxygenic photosynthesis, various electron donors are used. Cytochrome b 6 f and ATP synthase work together to produce ATP (photophosphorylation) in two distinct ways.
Chlorophyll a is very important in the energy phase of photosynthesis. Two electrons need to be passed to an electron acceptor for the process of photosynthesis to proceed. [5] Within the reaction centers of both photosystems there are a pair of chlorophyll a molecules that pass electrons on to the transport chain through redox reactions. [20]
Cyanobacteria such as these carry out photosynthesis.Their emergence foreshadowed the evolution of many photosynthetic plants and oxygenated Earth's atmosphere.. Biological carbon fixation, or сarbon assimilation, is the process by which living organisms convert inorganic carbon (particularly carbon dioxide, CO 2) to organic compounds.
C 4 fixation is an addition to the ancestral and more common C 3 carbon fixation. 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.
The electron flow produced by the reaction center chlorophyll pigments is used to pump H + ions across the thylakoid membrane, setting up a proton-motive force a chemiosmotic potential used mainly in the production of ATP (stored chemical energy) or to reduce NADP + to NADPH.
The photosynthetic efficiency (i.e. oxygenic photosynthesis efficiency) is the fraction of light energy converted into chemical energy during photosynthesis in green plants and algae. Photosynthesis can be described by the simplified chemical reaction 6 H 2 O + 6 CO 2 + energy → C 6 H 12 O 6 + 6 O 2
Reaction centers are present in all green plants, algae, and many bacteria.A variety in light-harvesting complexes exist across the photosynthetic species. Green plants and algae have two different types of reaction centers that are part of larger supercomplexes known as P700 in Photosystem I and P680 in Photosystem II.
Examples are chlorophyll, which is used by plants for photosynthesis and hemoglobin, the oxygen transporter in the blood of vertebrate animals. In these two examples, a metal is complexed at the center of a tetrapyrrole macrocycle ring: the metal being iron in the heme group (iron in a porphyrin ring) of hemoglobin, or magnesium complexed in a ...