Hybridization-based methods for measuring transcript levels
The natural structure of DNA is in the form of an anti-parallel double helix with each strand possessing a negatively charged phosphate backbone opposite nitrogenous bases, which are capable of donating hydrogen bonds. The precise geometry of the different bases means that these hydrogen bonds are donated to other bases placed in opposition to them in an antiparallel fashion using the classic Watson-Crick base pairing rubric: A=T and GC. These pairs of bases are said to be ‘complementary’ to one another. Pairs of complementary nucleotides can form hydrogen bonds in solution, but if two complementary polynucleotides come together, the strength of the hydrogen-bond attraction between the molecules is equal to the sum of all the individual nucleotide interactions. Pure genomic DNA consists of two perfectly complementary strands.