Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions used in the development and function of many viruses and organisms of all known. And protein and RNA, DNA is one of the three major macromolecules essential for the known forms of life all together. The DNA molecules most, No chain helical two-consisting of units long biopolymer two simple, called nucleotides, (guanine, adenine, thymine, and cytosine), each nucleotide, nucleobase G that has been recorded by the letter T C and which is composed of a backbone of alternating (associated with the phosphate) phosphoric acid group sugar sugars related (G, A, T, C) in the nucleotide bases and (deoxyribose). DNA backbone is resistant to tearing, the DNA so as to provide information that is duplicated encoded chip, two-stranded molecular structure, is suitable for this biometric information stored.

Image of DNA chain

In order to run in the opposite direction to each other, the backbone of single anti-parallel, both chains (5 prime) DNA, the 5 ‘and other (3 prime)’ 3. This is a molecule in-plane direction of the first five-carbon sugar and a third. (Informally, bases) is one of four types of molecules called nucleic acid bases in each sugar. This is a sequence  of nucleotide bases encoding the four skeletal genetic information. This information is read by means of the genetic code that determines the sequence of amino acids in the protein. RNA associated with the nucleic acid process called transcription, the code is read by copying a portion of the DNA.

In the cell, DNA is organized into long structures called chromosomes. Provides a complete set of chromosomes, each with its own cell, these chromosomes are repeated in the process of DNA replication during cell division. In organelles such as chloroplasts and mitochondria (protist animals, plants, and fungi) eukaryotic stores most of the DNA in the nucleus of some of the DNA and cells. I want to save the DNA of their own in the cytoplasm (bacteria, archaea) only in contrast to the prokaryotes. Within the chromosomes, chromatin proteins as compact organization of DNA and histone like this. The resulting interactions between proteins and other DNA, compact structure of these, helps to control transcription, a part of the DNA throat. 1953 pre-genetics, for example, is likely to encounter from time to time synonym “deoxyribonucleic acid” out-of-date.

The DNA, to grow and function, modern life of all, contains the genetic information to be able to reproduce. However, the form of the initial learning, it is possible to use RNA as its genetic material because it is proposed, the history of the DNA of life 40 million years, the length of time that perform this function is unknown it is. As it can send genetic information both to perform catalysis as part of the ribozyme, RNA can not function as a central part of cellular metabolism early. RNA nucleic acid can be the basis of the nucleotide bases of the four of the ancient world were used for genetics catalyst and affect the development of the genetic code now. Because it is a compromise between the number of bases of organisms such as the number of bases of different small, the accuracy of replication is improved, a large number of databases occurs increase the catalytic efficiency of the ribozyme is this.

However, direct evidence of the genetic system of ancient, never recovery of DNA from most fossils is not possible as. DNA is to survive in the environment for thousands of years at least, to be broken down into small pieces in the solution slowly. For reporting of separation of bacteria that could be done from a 250 million year old salt crystals most, claims of large DNA was made, but these claims had been discussed. On August 8, based on NASA research of meteorites on Earth, report in 2011, is extraterrestrially formed in outer space (related organic molecules adenine, and guanine,) block of the DNA of the building It was published to suggest the possibility.

Structure of part of DNA double link

In general, helix DNA occupies an area of ​​another core called “chromosome territory” even if it is not reacted with other segments of the DNA of human cells of different chromosomes. This physical separation of different chromosomes, it is important for the ability of DNA to Where to function storage so that the reaction of crossover of chromosome stably information such as the number of times between the chromosome, such as changing is. The DNA helices 2, after replacing the part breaking, crossover of chromosomes is when you join.

Recombination to produce a new combination of genes can be important to develop rapid and allows chromosomal genetic information exchange, increase the effectiveness of natural selection, a new protein. Further transgenic cells, in response to double-strand breaks in particular, it may be included in the DNA repair.

The most common form of mutual homologous recombination of chromosomes having a sequence very similar chromosomes that both participate. Because it can cause genetic abnormalities and chromosomal translocation that non-homologous recombination, can be harmful to the cells. In the recombination reaction that is catalyzed by an enzyme known as RAD51 recombinase, such as the. The first step in recombination is a DNA damage or, caused by endonuclease or double-stranded,. Series of steps catalysed in part by recombinase leads to connect the nodes Holliday one spiral at least two are annealed to the complementary strand spirally the other segment strand in each strand. It is possible to move along a pair of another chromosome, connecting substituted tetrahedral structure Holiday junction, and the chain. The recombination reaction is terminated by re-connecting unit and cutting of the DNA that was released subsequently.