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Deoxyribonucleic Acid

Components of DNA

DNA is a polymer.  A polymer is a very long molecule made up of many monomers.  Other examples of polymers are nylon, plastics, and polyester.  Polymers have many uses for man, and now we know that the very defining molecule for life is a polymer!

The monomer units of DNA are nucleotides, and the polymer is known as a "polynucleotide." Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the sugar, and a phosphate group. There are four different types of nucleotides found in DNA, differing only in the nitrogenous base. The four nucleotides are given one letter abbreviations as shorthand for the four bases.

You've probably seen these four letters before from watching TV.   Billions of these letters, just these four, in a row define one of these molecules.  The search for the order of these billions of letters is called the "Human Genome Project," and from these studies, it is expected that many diseases will have much new light shed on them, and some of them will be curable for the first time.

To Grandpa, the greatest miracle of them all is the miracle that relates us to all living things.  The discovery of DNA forty or so years ago is making that miracle a little clearer.  The order of those letters defines a human or a dog, a spider or a tree, or any other living thing on Earth.  This order also defines this human or that human and all the variation.  All the things that are the same in a pair of identical twins are defined here in this strand of DNA.  Those things that are different in the twins come from the environment - their experiences.

Life may not work the same way in other places in the universe.  (Ah - to be around for the next 50 years.)

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