DNA (DEOXYRIBONUCLEIC ACID)
Deoxyribonucleic Acid or DNA is a long molecule that is shaped like a double helix and resides in the nucleus or control center of the cell. The structure of DNA molecules helps insure that accurate copies are made when the cell divides. The cells that do the copying have “proof-reading” mechanisms which correct most copying errors. Like human proofreaders, however, these cellular devices sometimes make mistakes when the cells divide. Because the genome is copied many times for each generation, there are many slightly different versions of all the human genes.
Many of these “mistakes” are harmless and, indeed, are partly what gives each of us our unique characteristics. Except for identical twins, no two people have exactly the same sequence of DNA bases in their genes. Differences in the DNA sequence are so unique to an individual that DNA analysis can be used for identification.
DNA – and Genes: Genes are pieces of the famous long molecule known as deoxyribonucleic acid or DNA. Genes are located along the chromosomes in the nuclei, the control centers of cells. The information carried in genes is a code. It is the sequence of chemical units—called bases—strung together in that section of DNA. Information on this page is also a code made up of the sequence of individual letters. Each letter carries little information in itself, but strung together in the specific sequences, the letters make up words, sentences, and entire books.
The genetic “alphabet” has only 4 “letters” or bases, arranged in a sequence in each gene. The sequence of bases in a gene tells a cell how to assemble a specific protein.
