discovered DNA

When the gene and found that the link between DNA, people still like to know how this DNA is a kind of things, it is also what specific approach to the lives of so many information to the new successor does » First of all people want to know what DNA is composed of human love is always asked at the end of this shaver. The results have a called Levin of scientists through research, found that DNA from four of the smaller things, these four things name is the total nucleotide, like four brothers, all of them named nucleotide, But names are different, are adenine (A), guanine (G), cytosine (C) and thymine (T), the four names to remember, but remember that as long as the DNA is from four Nucleotide only casually together, and they have no connection to each other laws, but later nucleotides in fact not the same, and their mutual combination of the ever-changing methods of great mystery. Now, people have basically learned about the genetic How did it happen. The 20th century biological research found that: the human body is composed of cells, cell by cell, composed of the nucleus and cytoplasm. Known in the nucleus of a substance called chromosomes, it is called by some major deoxyribonucleic acid (DNA) of the material composition. Of the genetic material exists in all cells, this kind of material called DNA. DNA from the nucleotide polymerization. And each nucleotide phosphate, ribose and a base. There are five bases, respectively, adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U). Each contains only the five nucleotide base pairs in one. Even a single nucleotide into a chain, linked by two nucleotide a certain order, and then twisted into a "Serratula" kind, a deoxyribonucleic acid (DNA) of the molecular structure. In this structure, every three bases can form a genetic "password" and a DNA base pairs on as many as several million, so each DNA is a significant genetic code books, the inside of the genetic information In countless more, this DNA molecule found in the nucleus on the chromosome. They will pass with cell division genetic code. The genetic traits from the password to pass. Probably have 25,000 genes, and each gene is determined by the password. The same gene in both parts have different parts. Different parts of the difference between people decided that human diversity. A total of 3 billion DNA genetic code, are composed of about 25,000 genes. [Structure] [Edit this paragraph] DNA is composed of many deoxynucleotidyl residues with each other by a certain order of 3 ', 5'-phosphate ester bond linked to a long chain. Most of DNA containing two such long-chain, and some DNA for single-chain, such as E. coli phage φ X174, G4, M13, and so on. Some DNA for the ring, some for the linear DNA. Mainly with adenine, guanine, thymine and cytosine four kinds of bases. In some types of DNA, 5 - cytosine-to a certain extent can replace the CD, wheat germ DNA of 5 - methyl cytosine particularly rich, up 6 percent Moore. In some phage, 5 - hydroxymethyl cytosine replaced the CD. The late 1940s, Chargaff (E. Chargaff) found that different species of DNA base pairs of different, but the number of adenine equivalent to the number of its thymine (A = T), guanine cytosine equal to the number of (G = C), and thus the number of purine equivalent to the number of and pyrimidine. General painted with several levels of DNA structure. A structure of DNA in a structure that is its base sequence. Gene is a fragment of DNA, the genetic information stored in its genetic sequence of. 1975 U.S. Gilbert (W. Gilbert) and the United Kingdom Sanger (F. Sanger) respectively, created the structure of DNA a rapid determination of their total for the year 1980 Nobel Prize in Chemistry. Since then, determination and constantly improved, many of the DNA structure of an established. If people ring of mitochondrial DNA contains 16,569 base pairs, λ phage containing 48,502 DNA base pairs, rice chloroplast genome of 134,525 base pairs, tobacco chloroplast genome of 155,844 base pairs, and so on. Now the U.S. has plans to 10-15 years in all human DNA molecule of about 3 billion nucleotide pairs out of sequence. Secondary structure in 1953, Watson (Watson) and Crick (Crick) to the basic structure of DNA fibers is the double helix structure, but this model, the scientists acknowledged, and to explain reproduction, transcription and other important life process. After in-depth study and found that because of humidity and the base sequence of different conditions, DNA double helix can have many types, mainly divided into A, B and Z three categories. Is generally believed that, B configuration of the nearest cell in the DNA conformation, it is the double helix model is very similar. A-DNA and RNA molecules in the double helix, as well as the formation of transcription, DNA-RNA hybrid molecular conformation close. Z-DNA nucleotide dimer as a unit to the left to the winding, its main chain was serrated (Z) form, Gu Ming. This configuration of the chain for more than purine nucleotide pyrimidine alternate area. 1989, U.S. scientists used scanning tunneling electron microscope method to directly observe the DNA double helix DNA double helix: in 1952, Austria-American biochemists Chargaff (E.chargaff, 1905 -) of the DNA base pairs in the four kinds of Content found gland fat methotrexate and equal to the number of thymine, cytosine bird fat methotrexate and the number of the same. This makes Watson, Crick immediately think of four kinds of bases exists between the corresponding relations between February 2 and formed a gland fat methotrexate and thymine pairs, the birds fat methotrexate cytosine pairs with the concept. DNA replication [Edit this paragraph] DNA is the carrier of genetic information, the parent must take their own DNA molecule as a template accurate reproduction into two copies, and assigned to the two daughter cells, go to complete its mission of the carrier of genetic information. And the double-stranded DNA structure of this type of genetic material for the maintenance of the stability and the accuracy of reproduction are extremely important. (A) DNA copy of the semi-reservation Click Waston and raised in the DNA double helix structure on the model of DNA replication during the process of the study, they speculate, DNA base pairs in the process of copying the hydrogen bonds between the first fracture, double helix of the Rotary separately, were linked to each template Synthesis of the new chain, each offspring of a DNA chain from the pro-generation, and the other is a new synthesis, so as to retain a half-copy (semiconservative replication). (B) DNA replication 1. DNA double helix of the rotation (1) single chain DNA-binding protein (single-stranded DNA binding protein, ssbDNA protein) (2) DNA helicase (DNA helicase) (3) DNA of the chain 2. Okazaki fragments and a half does not copy a row 3. Copy the trigger and termination (C) telomeres and telomerase 1941-American Indians McClintock (Mc Clintock) raised a telomere (telomere) of the hypothesis that the chromosome ends must exist a special structure - the telomere. Telomere now known at least two roles: ① chromosome end protection from damage to chromosomes remained stable; ② and nuclear fiber-connected so that the chromosome can be targeted. [DNA of the physical and chemical properties -- [Edit this paragraph] DNA is macromolecular polymers, DNA solution for the polymer solution, with very high viscosity. DNA on the role of ultraviolet radiation is absorbed, when the nucleic acid degeneration, the absorption value increased when the degeneration of the nucleic acid can be complex, absorption values will be restored to the original level. Temperature, organic solvents, acidity, urea, amide, and other reagents DNA molecules can cause degeneration, even in the DNA double bond between the hydrogen bond breaking double helix structure untied. DNA (deoxyribonucleic acid) that DNA (genes and chromosomes an integral part of) deoxynucleotidyl the polymer, is the major components of chromosomes. The vast majority of genetic information stored in the DNA molecule. [Distribution and function -- [Edit this paragraph] Prokaryotic cell chromosome is a long DNA molecule. Eukaryotic cells in more than one chromosome, each chromosome containing only a DNA molecule. But their general than the original cells in the DNA molecule and protein and the combination. DNA molecule's function is the storage of all species decision RNA structure of the protein and all the genetic information; orderly planning of cells and tissue components of the time and space; identified throughout the life cycle of biological activity and identify biological personality. In addition to chromosomal DNA, a very small amount of the different structure of DNA found in eukaryotic cells in the mitochondria and chloroplasts. DNA of the virus genetic material is DNA. [The discovery of DNA -- [Edit this paragraph] Since the genetic Mendel's law was re-discovered, the people also raised a question: genetic factor is not a material entity » In order to solve the problem of what is, people began to DNA and protein research. As early as 1868, people have discovered DNA. German chemist in the laboratory Huopei Siler, a Swiss post-graduate名叫米歇尔(1844 - 1895), his lab near a hospital threw the bandage with a sense of Nongxue Interest, because he knows that those Nongxue to defend human health, germs and "combat" and died in the WBC and was killed in human cells, "body." So he carefully the bandage on the Nongxue collected and used pepsin decomposition, and found the bodies of most of the cell decomposition, but the nuclear non-functional. He further material within the nucleus of an analysis and found that cells containing a phosphorus and nitrogen-rich material. Huopei Siler experiments with yeast, that the nucleus Michel substances found to be correct. So he would give such a separation from the nucleus of the material named "nuclide", and later it was discovered that it was acidic, so to call "DNA." From then on the people of nucleic acid carried out a series of fruitful research.