The order in which the bases occur determines the information available, much as specific letters of the alphabet combine to form words and sentences. The DNA in each of the body's cells is organized into what are known as chromosomes. The DNA in each chromosome contains many genes. A gene is a segment of a chromosome that encodes instructions that allow a cell to produce a specific product, typically a protein, that initiates one specific action. There are between 50,000 and 100,000 genes and every gene is made up of thousands, even hundreds of thousands, of chemical bases.
Many diseases have their roots in our genes.
A sound body depends upon the continuous interplay of thousands of proteins, acting together in just the right amounts and in just the right places. Each properly functioning protein is the product of a working gene. Genes can be altered, or mutated, in many ways that affect their ability to work. The most common gene mutation involves a single changed base in the DNA - a misspelling. Other alterations include the loss or gain of a base.