DeoxyriboNucleic Acid (DNA)
The Genetic Code
The four DNA nucleotides are called:
Cytosine, Guanine, Adenine and Thymine
Giving us the four letters of the genetic code – C G A T
DNA is found in almost every living cell in our bodies and furthermore every individual cell contains a full copy of the complete genetic code. The code contains our blueprint including all of the information that determines what we physically are. A fertilized egg, for example, converts the information in the genetic code to create a completely new and unique individual. Cells in the bodies of adults use the genetic code to build and maintain body tissues and organs as well as many other body functions. Fundamentally, the only difference between individual people, and indeed the only difference between species, is the sequence in which the nucleotides appear in their DNA. The complete genetic code for a species is called its genome as in the “human genome”. For a brief description of the main testing methods you will encounter if you pursue your own DNA tests go to DNA Testing Methods.
How Can Our DNA Carry So Much Information?
The human genome is contained within 23 long pieces of DNA, called chromosomes, found in the nucleus of each cell. In all non-sex cells (that is every cell except sperm and egg cells) there is a double copy of the 23 chromosomes, the so-called chromosome pairs. One set of 23 chromosomes contains over 3 billion nucleotides within its DNA strands. If you unraveled the DNA strands in the 23 chromosomal pairs from a single cell and laid them end-to-end they would stretch to 2 meters or 6.5 feet! If you consider your body contains around 10 trillion cells then all of your DNA placed end-to-end would wrap around the earth’s equator many thousands of times.
(If you’d like more detail on the structure of DNA click the following link: What Is DNA)
Now that you know a DNA strand consists of a long chain of DNA nucleotides and four different nucleotides form the letters of the genetic code, you know enough about the structure of DNA to help you understand how it does its job. You now have the basic foundation to help you understand how DNA testing can be used to discover things like how humans are related, what is our ancestry and what is our own personal susceptibility to diseases and disorders. Modern DNA technology is increasingly giving us affordable tools to quickly and easily discover things about our own personal DNA code and find out lots of information about ourselves, our relatives and our ancestors. There are a number of different ways in which you can test your DNA. The different tests tell you different things about yourself and your genetic history – find out about the basics of each method.