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.
A DNA strand is made up of hundreds of thousands of nucleotides put together. A nucleotide is a type of molecule (organic molecule, to be specific) that is made up of a phosphate, a sugar, and a nitrogen base. In all DNA nucleotides, there is always the same phosphate and sugar. But the nitrogen bases differ. There are four nitrogen bases in DNA--Adenine, Guanine, Cytosine, and Thymine.