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Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc, Cylindrospermum, and Anabaena. [1] They fix nitrogen from dinitrogen (N 2 ) in the air using the enzyme nitrogenase , in order to provide the cells in the filament with nitrogen for biosynthesis.
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
Aphanizomenon are a special type of cyanobacteria called heterocysts, which are capable of producing biologically useful nitrogen by the process of nitrogen fixation from atmospheric nitrogen. A large proportion (between 35 and 50%) of fixed nitrogen may be released into the surrounding water, providing an important source of biologically ...
An electrode in which oxidation takes place is called an anode while in that which reduction takes place is called cathode. This applies for both electrolytic and electrochemical cells, though the charge on them reverses. The red cat and an ox mnemonics are useful to remember the same. Red cat: Reduction at cathode; An ox: Anode for oxidation. [32]
Some cyanobacteria can fix atmospheric nitrogen in anaerobic conditions by means of specialized cells called heterocysts. [ 59 ] [ 60 ] Heterocysts may also form under the appropriate environmental conditions (anoxic) when fixed nitrogen is scarce.
Many cyanobacteria form motile filaments of cells, called hormogonia, that travel away from the main biomass to bud and form new colonies elsewhere. [45] [46] The cells in a hormogonium are often thinner than in the vegetative state, and the cells on either end of the motile chain may be tapered. To break away from the parent colony, a ...
Heterocysts function to convert environmental nitrogen (N 2) into compounds such as ammonia or nitrate. Nitrogenase , an oxygen-sensitive enzyme, is essential to this conversion. For the proper functioning of nitrogenase, the intracellular environment of the heterocyst must be anaerobic , a task achieved by the oxygen-impermeable structure of ...
Hopefully, they have managed to reach the plant host by this time. The bacteria then differentiate specialized nitrogen-fixing cells called heterocysts and enter into a working symbiosis with the plant. Depending on species, Hormogonia can be many hundreds of micrometers in length and can travel as fast as 11 μm/s.