DNA Tests

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost every other organism. Almost every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

The information in DNA is stored as a code, this code is made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

Human DNA consists of roughly 3 billion bases, and more than 99 percent of those bases are identical in all people. The order and sequence, of these bases determines the information available to building and maintain an organism, this is similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.

DNA bases pair up with each other, A with T and C with G, to form units, these units are called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. When these are together, the base, sugar, and phosphate are called a nucleotide. The nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is resembles a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.

An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix serves as a pattern for duplicating the sequence of bases. This is crucial when the cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.