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Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3.4 billion years old. [59] [60] More recent studies also suggest that photosynthesis may have begun about 3.4 billion years ago, [61] [62] though the first direct evidence of photosynthesis comes from thylakoid membranes preserved in 1.75-billion-year-old ...
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 ...
If electrons only pass through once, the process is termed noncyclic photophosphorylation, but if they pass through PSI and the proton pump multiple times it is called cyclic photophosphorylation. When the electron reaches photosystem I, it fills the electron deficit of light-excited reaction-center chlorophyll P700 + of PSI.
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.
The enzyme phosphoglycerate kinase catalyses the phosphorylation of 3-PGA by ATP (which was produced in the light-dependent stage). 1,3-Bisphosphoglycerate (glycerate-1,3-bisphosphate) and ADP are the products. (However, note that two 3-PGAs are produced for every CO 2 that enters the cycle, so this step utilizes two ATP per CO 2 fixed ...
There are three major metabolic pathways by which photosynthesis is carried out: C 3 photosynthesis, C 4 photosynthesis, and CAM photosynthesis. C 3 photosynthesis is the oldest and most common form. A C3 plant uses the Calvin cycle for the initial steps that incorporate CO 2 into organic material.
If you can answer 50 percent of these science trivia questions correctly, you may be a genius. The post 50 Science Trivia Questions People Always Get Wrong appeared first on Reader's Digest.
Carbon on Earth naturally occurs in two stable isotopes, with 98.9% in the form of 12 C and 1.1% in 13 C. [1] [8] The ratio between these isotopes varies in biological organisms due to metabolic processes that selectively use one carbon isotope over the other, or "fractionate" carbon through kinetic or thermodynamic effects. [1]