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Hüfner had suggested that the oxygen-haemoglobin binding curve was hyperbolic in shape, [5] but after extensive experimentation, the Copenhagen group determined that the curve was in fact sigmoidal. Furthermore, in the process of plotting out numerous dissociation curves, it soon became apparent that high partial pressures of carbon dioxide ...
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.
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]
Carbonic acid is a chemical compound with the chemical formula H 2 C O 3.The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is quite stable at room temperature.
Carbonic anhydrase is a very ancient enzyme found in both domains of prokaryotes that exists in six different classes among most of the living organisms. [11] These families are not similar in sequence or structure because they evolved independently of each other, but all evolved the same Zn 2+ active site structure, showing a great example of ...
The carbon dioxide molecules form a carbamate with the four terminal-amine groups of the four protein chains in the deoxy form of the molecule. Thus, one hemoglobin molecule can transport four carbon dioxide molecules back to the lungs, where they are released when the molecule changes back to the oxyhemoglobin form.
The symmetry of a carbon dioxide molecule is linear and centrosymmetric at its equilibrium geometry. The length of the carbon–oxygen bond in carbon dioxide is 116.3 pm, noticeably shorter than the roughly 140 pm length of a typical single C–O bond, and shorter than most other C–O multiply bonded functional groups such as carbonyls. [19]
In 2011 the OEC of PSII was resolved to a level of 1.9Å revealing five oxygen atoms serving as oxo bridges linking the five metal atoms and four water molecules bound to the Mn 4 CaO 5 cluster; more than 1,300 water molecules were found in each photosystem II monomer, some forming extensive hydrogen-bonding networks that may serve as channels ...