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blocks” of which our body is made. There are trillions of them, some functioning for a lifetime, while others are shed and replaced every few days. The concept of the simple cell, that satisfied foremost biologists a generation ago, is no longer adequate today. Cells are miniature factories with complicated enzyme systems and little organs (called organelles) that manufacture, store, package, defend, design, and even reproduce cells after their kind. Central to the design of each cell is its nucleus. This specialized inner portion contains the hereditary material we call DNA. Containing the code for structural proteins, as well as its master plan for reproduction, this DNA (deoxyribonucleic acid) is wound in the shape of an alpha-helix, containing four basic groups of nitrogenous rings (guanine, cytosine, adenine, thymidine) linked through phosphate bonds to the five-carbon sugar, deoxyribose. This combination of genetic codes makes possible practically an infinite variety of human beings. Simple features of hair color, body shape, and native intelligence, as well as the more complex human features which give us our individuality, are determined by the DNA molecule. Reproduction involves the genetic combining of one-half the DNA structure from the sperm and the other half from the ovum. In reproductive cell division, called meiosis, the number of chromosomes (usually, human cells contain 46) is reduced by half, allowing two germ cells to combine and make up a full chromosome complement for the fertilized egg (called the zygote). Cell division then occurs to create the beginnings of an embryo. This follows the usual plan of mitosis, where identical “daughter cells” are produced with each division. It has been estimated that the possibility for variations and differences in the hemoglobin molecule alone is of the order l x 10 146 (this means the number one followed by 146 zeros). Thus, the probability of this marvelous event occurring by chance or evolving over long eons of time is virtually nil! Other parts of the cell are equally marvelous. The mitochondrion is a tiny “organ” within the cytoplasm of the cell. It is in this structure that food processing takes place for the production of energy. For that reason, it is sometimes called a “power house.” Oxygen is required to utilize various vitamins and minerals as cofactors in the conversion of food to energy. The Golgi apparatus is a packaging plant where enzymes, mucus, and other products of the cell’s metabolism are stored in parcels, ready to be released. Closely related to protein synthesis in each cell is the endoplasmic reticulum, which provides a operational base for the ribosomes. These small packages of RNA (ribonucleic acid) constitute the location for our structural genes, that direct the manufacture of protein molecules. They, seemingly, are “turned” on or off like a thermostat in a type of servo—control mechanism.