BIOLOGICAL EFFECTS OF RADIATION Chromosomes, Genes, and DNA Like the whole beach we mentioned that is composed of tiny grains of sand and smaller particles, our bodies are composed of tiny cells. These cells, which have different functions and different shapes, have nuclei, or centers. all Within these centers are string-like materials called chromosomes, which are in turn made up of genes. The genes are also composed of a number of chemicals, the most important of which is DNA, short for desoxyribonucleic acid. All of these things are composed of molecules and, their smaller parts, atoms. These chromosomes, which are a series of long and short worm-like or thread-like shapes, determine the workings and divisions of the cell. The genes, which are like different bands of color or segments on a thread, each serve a function in making up the form of the chromosome. form the genes. The DNA and other chemicals These chemicals contain codes, or chemical signals which regulate the shape, form, and life of the genes. The genes then determine the shape and form of the chromosome, and the chromosome the shape and function of the cell. The cells ultimately control the shape and form of our bodies. Almost all the cells in our body are continuously producing new cells, some slower, some faster. It is easier to understand if we consider that when we cut our hair, or fingernails, they grow again. If we get a cut or burn, the blood lost will be replaced, or the skin damaged will be replaced. This is done by the cells reproducing, or duplicating themselves, and it is the basic process which allows us to grow to 23 Wai028