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Adenosine triphosphate

Adenosine triphosphate is a complex organic chemical that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, chemical synthesis. Found in all forms of life, ATP is referred to as the "molecular unit of currency" of intracellular energy transfer; when consumed in metabolic processes, it converts either to adenosine diphosphate or to adenosine monophosphate. Other processes regenerate ATP so that the human body recycles its own body weight equivalent in ATP each day, it is a precursor to DNA and RNA, is used as a coenzyme. From the perspective of biochemistry, ATP is classified as a nucleoside triphosphate, which indicates that it consists of three components: a nitrogenous base, the sugar ribose, the triphosphate. In terms of its structure, ATP consists of an adenine attached by the 9-nitrogen atom to the 1′ carbon atom of a sugar, which in turn is attached at the 5' carbon atom of the sugar to a triphosphate group. In its many reactions related to metabolism, the adenine and sugar groups remain unchanged, but the triphosphate is converted to di- and monophosphate, giving the derivatives ADP and AMP.

The three phosphoryl groups are referred to as the alpha, and, for the terminal phosphate, gamma. In neutral solution, ionized ATP exists as ATP4−, with a small proportion of ATP3−. Being polyanionic and featuring a chelatable polyphosphate group, ATP binds metal cations with high affinity; the binding constant for Mg2+ is. The binding of a divalent cation always magnesium affects the interaction of ATP with various proteins. Due to the strength of the ATP-Mg2+ interaction, ATP exists in the cell as a complex with Mg2+ bonded to the phosphate oxygen centers. A second magnesium ion is critical for ATP binding in the kinase domain; the presence of Mg2+ regulates kinase activity. Salts of ATP can be isolated as colorless solids. ATP is stable in aqueous solutions between pH 7.4, in the absence of catalysts. At more extreme pHs, it hydrolyses to ADP and phosphate. Living cells maintain the ratio of ATP to ADP at a point ten orders of magnitude from equilibrium, with ATP concentrations fivefold higher than the concentration of ADP.

In the context of biochemical reactions, the P-O-P bonds are referred to as high-energy bonds. The hydrolysis of ATP into ADP and inorganic phosphate releases 30.5 kJ/mol of enthalpy, with a change in free energy of 3.4 kJ/mol. The energy released by cleaving either a phosphate or pyrophosphate unit from ATP at standard state of 1 M are: ATP + H2O → ADP + Pi ΔG° = −30.5 kJ/mol ATP + H2O → AMP + PPi ΔG° = −45.6 kJ/mol These abbreviated equations can be written more explicitly: 4− + H2O → 3− + 3− + 2 H+ 4− + H2O → 2− + 4− + 2 H+ A typical intracellular concentration of ATP is hard to pin down, reports have shown there to be 1–10 μM per gram of tissue in a variety of eukaryotes. The dephosphorylation of ATP and rephosphorylation of ADP and AMP occur in the course of aerobic metabolism. ATP can be produced by a number of distinct cellular processes; the overall process of oxidizing glucose to carbon dioxide, the combination of pathways 1 and 2, is known as cellular respiration, produces about 30 equivalents of ATP from each molecule of glucose.

ATP production by a non-photosynthetic aerobic eukaryote occurs in the mitochondria, which comprise nearly 25% of the volume of a typical cell. In glycolysis and glycerol are metabolized to pyruvate. Glycolysis generates two equivalents of ATP through substrate phosphorylation catalyzed by two enzymes, PGK and pyruvate kinase. Two equivalents of NADH are produced, which can be oxidized via the electron transport chain and result in the generation of additional ATP by ATP synthase; the pyruvate generated. Glycolysis is viewed as consisting of two phases with five steps each. Phase 1, "the preparatory phase", glucose is converted to 2 d-glyceraldehyde -3-phosphate. One ATP is invested in the Step 1, another ATP is invested in Step 3. Steps 1 and 3 of glycolysis are referred to as "Priming Steps". In Phase 2, two equivalents of g3p are converted to two pyruvates. In Step 7, two ATP are produced. In addition, in Step 10, two further equivalents of ATP are produced. In Steps 7 and 10, ATP is generated from ADP.

A net of two ATPs are formed in the glycolysis cycle. The glycolysis pathway is associated with the Citric Acid Cycle which produces additional equivalents of ATP. In glycolysis, hexokinase is directly inhibited by its product, glucose-6-phosphate, pyruvate kinase is inhibited by ATP itself; the main control point for the glycolytic pathway is phosphofructokinase, allosterically inhibited by high concentrations of ATP and activated by high concentrations of AMP. The inhibition of PFK by ATP is unusual, since ATP is a substrate in the reaction catalyzed by PFK; the protein has two binding sites for ATP – the active site is accessible in either protein conformation, but ATP binding to the inhibitor site stabilizes the conformation that binds F6P poorly. A number of other small molecules can compensate for the ATP-induced shift in equilibrium conformation and reactivate PFK, including cyclic AMP, ammonium ions, inorganic phosphate, a

Ivan Kazakov

Ivan Semyonovich Kazakov (Russian: Иван Семёнович Казаков. He was born to a family of farmers. From 1888 to 1894, he studied at the Moscow School of Painting and Architecture, he continued at the Imperial Academy of Arts under Vladimir Makovsky and was awarded the title of "Artist" in 1898. His title included a stipend to study abroad so, from 1899 through 1900, he travelled to Italy and Germany. Upon returning, he settled in Saint Petersburg. For the next decade, he was a frequent exhibitor there and in Moscow. In 1906, he requested and obtained a position as a teacher of drawing and calligraphy at the Realschule in Tashkent, which he held until 1910. While there he painted architectural landscapes in Samarkand and Bukhara as well as Tashkent, he created a series of ethnographic sketches. He taught at a regional art school and, in 1921, established his own studio. On several occasions, he helped design revolutionary celebrations. During this time, he had showings at the first National Free Exhibition of Art in Saint Petersburg, the 47th exhibit of the Peredvizhniki in Moscow, the first exhibit of the Tashkent branch of the Russian Academy of Arts, of which he was one of the founders.

From 1926 to 1930, he was an organizing member of the Tashkent branch of the Association of Artists of Revolutionary Russia and headed their studio. In 1930, a feuilleton about Kazakov and his fellow-artist, Yeremey Burtsev, appeared in Pravda Vostoka, its pseudonymous author accused them of having their students paint figures of Christ and Saint Paul and suggested that the AKhRR branch in Tashkent be investigated by "Glavprofobra". This was done and the artists were charged with anti-Soviet agitation. A special board meeting by local members of the OGPU sentenced them to three years exile in Stalinabad. Burtsev's exile was extended. Kazakov spent his final years teaching at the Tashkent Polytechnic Institute. List of Orientalist artists Orientalism Media related to Ivan Kazakov at Wikimedia Commons

July 1982 lunar eclipse

A total lunar eclipse took place on July 6, 1982. The moon passed through the center of the Earth's shadow, it was seen over North and South America, seen rising over Australia, setting over Western Africa. There are seven eclipses in 1982, the maximum possible, including 4 partial solar eclipses: January 25, July 20, June 21, December 15. Lunar saros series 129, repeating every 18 years and 11 days, containing 71 events, has 11 total lunar eclipses; the first total lunar eclipse of this series was on May 24, 1910, last will be on September 8, 2090. The two longest occurrence of this series were on July 6, 1982 and July 16, 2000 when totality lasted 106 minutes, it last occurred on June 25, 1964 and will next occur on July 16, 2000. This is the 36th member of Lunar Saros 129; the previous event was the June 1964 lunar eclipse. The next event is the July 2000 lunar eclipse. Lunar Saros 129 contains 11 total lunar eclipses between 1910 and 2090. Solar Saros 136 interleaves with this lunar saros with an event occurring every 9 years 5 days alternating between each saros series.

The inex series repeats eclipses 20 days short of 29 years, repeating on average every 10571.95 days. This period is equal to 388.5 draconic months. Saros series increment by one on successive Inex events and repeat at alternate ascending and descending lunar nodes; this period is 383.6734 anomalistic months. Despite the average 0.05 time-of-day shift between subsequent events, the variation of the Moon in its elliptical orbit at each event causes the actual eclipse time to vary significantly. It is a part of Lunar Inex series 39. All events in this series listed below and more are total lunar eclipses. A lunar eclipse will be followed by solar eclipses by 9 years and 5.5 days. This lunar eclipse is related to two total solar eclipses of Solar Saros 136. List of lunar eclipses List of 20th-century lunar eclipses NASA: Lunar Eclipses: Past and Future 1982 Jul 06 chart Eclipse Predictions by Fred Espenak, NASA/GSFC Index to Five Millennium Catalog of Lunar Eclipses, -1999 to +3000 Eclipses: 1901 to 2000 Total Lunar Eclipse of 1982 July 06 Photo Gallery Photo mideclipse Vulcan Eclipse End of Totality July 6, 1982, by Jerry Lodriguss Bao-Lin Liu, Canon of Lunar Eclipses 1500 B.

C.-A. D. 3000, 1992