This quantity is high within highly methylated "islands" in the genome.
The algorithm IsoPlotter identifies regions with consistent values of this quantity, which are called "compositional domains." Giorgio Bernardi's group used high and low values of this quantity to respectively classify warm and cold blooded organisms. This quantity is uniform across regions called isochores. This quantity is low for organisms in Firmi∙cu∙tes but high for organisms in Actino∙bacteria. In mammals, the decrease in this quantity over evolutionary time can be attributed to spontaneous de∙amination. The annealing temperature of a primer in PCR depends on this quantity, because the melting point of a double-stranded DNA molecule is positively correlated with it. This quantity is high within highly methylated "islands" in the genome. For 10 points, name this value, the proportion of a DNA strand that consists of nitrogenous bases joined by three hydrogen bonds.
The algorithm IsoPlotter identifies regions with consistent values of this quantity, which are called "compositional domains."
GC content [or GC ratio or CG ratio or CG content or G+C content or C+G content; accept any answer describing the percentage of a genome that is cytosine AND guanine]