Nucleotides on the left are (top to bottom) 5'-Cyt-Gua-Ade-3'; on the right (BOTTOM to TOP) are 5'-Thy-Cyt-Gua-3' Blue denotes an exposed atom with somewhat positive charge; red somewhat negative. In the future, charges will be shown as translucent halos. Backbone phosphates are orange.
Do you see how if the two helices were rotated inwards toward one another, the pinks on one would clasp the blues on the other? THIS is specific matching of DNA strands!
Move molecules by clicking them and dragging in the window