If it is a long run, 16 gauge is preferred. If the run is very short, you probably can use 18 gauge with no apparent difference in sound. But the cost difference is fairly small, so 16 gauge is preferred. There is no shielding on speaker wire, so the covering is of little import.
The backbone of the DNA strand is made from alternating phosphate and sugar residues. The sugar in DNA is 2-deoxyribose, which is a pentose (five-carbon) sugar. The sugars are joined together by phosphate groups that form phosphodiester bonds between the third and fifth carbon atoms of adjacent sugar rings.
DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases.