genome.

    An alternative and more common o regard tructionmanual for ters and tructions for making proteins. tructions are ten are called codons, and tters are knoters of tic alp—consist of tides mentioned a page or two back:

    adenine, tosine. Despite tance of ances are not made of anytic. Guanine, for instance, is tuff tabounds in, and gives its name to, guano.

    taircase orted rope ladder: ts of tructure are made of a typeof sugar called deoxyribose, and teps) are formed by tosine and tters appear as youmove up or doitutes t .

    Noicular brilliance of DNA lies in its manner of replication.  is time toproduce a nerands part do, and eaco form a nenerside along astrand pairs up ide, eacrand serves as a template for tion of a necrand. If you possessed just one strand of your o tc tnerships:

    if topmost rung on one strand  topmost rung on tcrand must be cytosine. ork your ide pairings, and eventually you   t nature does it really quickly—inonly a matter of seconds, .

    Most of time our DNA replicates iful accuracy, but just occasionally—aboutone time in a million—a letter gets into tidepolymorpo biocs as a “Snip.” Generally tretcectable consequence for the body.

    But occasionally t leave you predisposed to some disease,but equally t confer some sligage—more protective pigmentation, forinstance, or increased production of red blood cells for someone living at altitude. Over time,t modifications accumulate in botions, contributing totinctiven