Herding Hemingway's Cats

The Old Man and the Cats with Six Toes

Famed author Ernest Hemingway was fond of polydactyl (six-toed) felines, and introduced them onto his estate in Key West, Florida. Their mutation springs from a fault in a deoxyribonucleic acid (DNA) “control switch,” and not from an error in the gene itself. The “letters” of DNA – A, C, T and G – stand for the chemical “bases” of adenine, cytosine, thymine and guanine. These string together in the familiar double helix in most cells in your body. In 1953, molecular biologists Francis Crick and James Watson deciphered the ladder-like double helix shape of the DNA molecule. The bases that compose the ladder’s “rungs” always pair together – A with T and G with C. Scientists call the specific order of the bases a “sequence.”

Chromosome Pairs

The 46 strings of DNA form into “23 pairs of chromosomes” inside each of your body’s cells; these constitute your genome. Women have two X chromosomes; men have an X and a Y chromosome. The chromosomes reside in the middle of the cell – in its nucleus. This is the DNA “library” from which “RNA polymerase...