Many would argue that chromosomes, genes, and DNA form the ineluctable essence of modern biology. Not only do these fundamental components of living cells provide moment-to-moment instructions by which cells carry out basic life processes, they also control inheritance of characteristics from one generation to the next. These essential functions of DNA stem from its repetitive structure. Hugely long DNA molecules are built from just four components, referenced by their singleletter abbreviations, A, C, G, and T. It is the specific sequence of these As, Cs, Gs, and Ts that constitutes the coded information of DNA. Moreover, molecular biologists have determined that this genetic code is universal, i.e., petunias, earthworms, chimpanzees, and everything else spell out their genetic instructions using the same three-letters-ata- time code words. We are now well into the genome era, in which biologists seek meaning by reading, for many organisms, the codes contained in the long strings of As, Cs, Gs, and Ts that encompass the totality of their DNA.
Copyright © 2015, Virginia Native Plant Society. This article first appeared in Sempervirens (Fall 2015), 4-5.
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Hayden, W. John. "There's Much Left to Learn: Clethra's Chromosomes. " Sempervirens, Fall 2015, 4-5.