stars and stripes 2 italics the national anthem of the united states of america based on a poem written by francis scott key on september 14 1814 and set by him to the melody of the english song to anacreon in heaven officially adopted by the u s congress in 1931 examples from the web for star spangled banner expand
The two strands of DNA are held together by weak hydrogen bonds (remember, something must hold them together!) between the nitrogenous bases. The interesting (and very important) aspect of the Watson-Crick model is that these hydrogen bonds are base specific.
Figure 1. Before a cell divides, its DNA is replicated (duplicated.) Because the two strands of a DNA molecule have complementary base pairs, the nucleotide sequence of each strand automatically supplies the information needed to produce its partner.f the two strands of a DNA molecule are separated, each can be used as a pattern or template to produce a complementary strand. Each template and its new complement together then form a new DNA double helix, identical to the original.