Snowflake unlikely that any two snowflakes are alike due to the estimated 10 (10 quintillion) water molecules which make up a typical snowflake, which grow at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere that the snowflake falls through on its way to the ground. Snowflakes that look identical, but may vary at the molecular level, have been grown under controlled conditions. Although snowflakes are never completely symmetrical, a non-aggregated snowflake often grows so as to exhibit an approximation of six-fold radial symmetry. The symmetry gets started due to the hexagonal crystalline structure
Bis(5'-nucleosyl)-tetraphosphatase (symmetrical) As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and . Bis(5'-nucleosyl)-tetraphosphatase (symmetrical) In enzymology, a bis(5'-nucleosyl)-tetraphosphatase (symmetrical) () is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are P1,P4-bis(5'-adenosyl) tetraphosphate and HO, whereas its product is ADP. This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides in phosphorus-containing anhydrides. The systematic name of this enzyme class is P1,P4-bis(5'-nucleosyl)-tetraphosphate nucleosidebisphosphohydrolase. Other names in common use include diadenosinetetraphosphatase (symmetrical), dinucleosidetetraphosphatasee (symmetrical), symmetrical diadenosine tetraphosphate hydrolase, adenosine tetraphosphate phosphodiesterase, Ap4A hydrolase, bis(5'-adenosyl)