You're thinking of the ball-and-stick model for much simplier chemical compounds. The template DNA strand is depicted as a twisted ladder. Across are the base pyrimidines and purine pairs (A-T and C-G). The bases are supported by a sugar phosphate backbone. There are 2 bonds between A & T and 3 between C & G. As a result, you wind up with major and minor grooves. Then there is the whole mess with nucleosomes, histone proteins, and the non-histone proteins so that the DNA can be compacted and uncompacted. ARGG! the forensic science grad student will now shut up to prevent brain overload