The information in DNA is carried as a code made up of four chemical bases of the structure: adenine (A), guanine (G), cytosine (C) and thymine (T). Human DNA consists of about three billion bases, and more than 99 percent of the base is the same for everyone. The order or sequence of these bases determines the information available to establish and maintain a body similar to the letters of the alphabet are displayed in a specific order to form words and sentences.
Adenine with thymine and cytosine with guanine pairs with each other, is a unit of base pairs of DNA. Molecules of sugar and phosphate molecules bound to each DNA base. nucleotide consists of a simple sugar base and phosphate. Nucleotides are arranged in two long chains that spiral or double helix. The structure is like a ladder with rungs of base pairs and the sugar molecules and phosphate components of the vertical scale.
An important property of DNA is that it can reproduce copies of themselves or each strand of the DNA double helix to serve as a model for duplication of base sequences. This is important when cells divide because each new cell is an exact copy of DNA must be in the old cell.
DNA sequence analysis is very useful in the study of evolutionary history. Several types of DNA sequences allowed the diversity of life and allow scientists to evolutionary relationships within groups of detailed analysis.
The potential benefits of large efforts to a target sequence of a single gene in all forms of life, the theme is "Taxonomy and DNA", a conference at Cold Spring Harbor Laboratory, March 9, 12, 2003. Participants of the conference are experts in animals, microorganisms and plant taxonomy, molecular biology and bioinformatics. The purpose of the sequencing project is a major practical method for the determination of species and provide an overview of the history of the evolution of life.
DNA sequencing was also used to try to identify and overcome the limits of the species in populations of organisms appeared to be similar. But using a confusing array of genes and analysis methods within DNA-based identification and phylogenetic research in general, limit the application of the results of certain groups in this study.