What are the implications of the linear, double-helical structure of DNA? First of all, it means that the cell is confronted with a packing problem. The genomic DNA for a multicellular organism, even one as primitive as, say, Dan Quayle, encompasses gazillions of base pairs—a DNA molecule several feet long if you stretched it out.  We’ll examine how the cell overcomes this problem when we look at chromosome structure.

More to the point, the structure of DNA, as worked out by Watson and Crick, answers the question of how DNA can serve as the genetic material. Clearly, the sequence of bases in each strand could serve as letters in a genetic alphabet, and the specific pairing of bases would allow one strand to serve as a template for the other. Or, as Watson and Crick noted rather drily in their Nobel-Prize winning paper in the journal Nature:

“It has not escaped our notice that the specific pairing we have postulated suggests a possible copying mechanism for the genetic material.”