The physicochemical properties of DNA

The physicochemical properties of DNA.
DNA is macromolecules polymer solution for polymer solution, DNA, has high viscosity. DNA to absorb uv, when there was light nucleic acid degeneration increase value, When the degeneration KeFuXing nucleic acid value, and will return to their former level. Temperature, organic solvents, ph, urea, amide, can cause the DNA molecule reagent, even to DNA double fracture of the double helix structure, hydrogen.
Deoxyribonucleic acid (DNA) refers to deoxyribonucleic acid (chromosomes and genetic component of deoxidizing), is the main properties chromosomes. Genetic information is stored in most parts of the DNA molecules.
This period of the distribution and editing functions.
Prokaryote cells chromosome is a long DNA molecules. The nucleus of more than one chromosomes, each containing a chromosome and only DNA molecules. But they usually prokaryote cells than the DNA molecule and large and protein together. DNA molecule function is stored decided all species of protein and RNA structure; all the genetic information, Planning is the synthesis of biological sequence components of cells and tissues of space and time, Biological throughout life cycle of activity and biological character. Besides chromosomes are a DNA, the structure of DNA exist in eukaryotic cells in the mitochondria and chloroplasts. DNA genetic material is the virus DNA.
This section of the DNA editor that.
Since Mendelian genetics was rediscovered, law of people and put forward a problem: genetic factor is a tangible? In order to solve the problem, it is something genes and proteins of nucleic acids was started.
Early in 1868, it has been discovered the nucleic acid. In Germany, the chemist HuoPei of lab, a graduate of Switzerland (1844 - named michelle, his lab 1895) to throw a nearby hospital with the bandage NongXie interested, because he knows that NongXie is to defend human health, and bacteria "combat" died and was killed and the white body cell "body". So he took the bandage carefully NongXie collected and decomposing pepsin, found that most of the body cells are decomposed, but to nuclei. He further analysis of nuclear material, found within the nucleus contains a rich phosphorus and nitrogen. The yeast, caleb HuoPei experimenting with that of nuclear material michel within that is correct. Then he gave the separated from the nucleus of material named ", "people later found nuclide acid, so it is often called" the nucleic acid. From then on, people of nucleic acid has conducted a series of effective research.
At the beginning of the 20th century, Germany, Serbia (1853, 1927) and his two students Jones (1865-1935) and 1940) -- lieven 1869 (the nucleic acid, the study of basic chemical structure, think it is composed by many nucleotides of molecules. Nucleotide bases, DNA is composed of phosphate. And There are four bases of adenocarcinoma, mere (Piao birds, and thymine bases cytosine), there are two (DNA), therefore, deoxyribose the nucleic acid into ribonucleic acid (DNA or RNA) (DNA).
Levin anxious about his research, mistakenly believe that four bases in the nucleic acid, which is equal to deduce the basic structure of nucleic acids by four different bases of nucleotides linked to four nucleotide, and based on this, put forward the nucleic acid polymer into four nucleotide hypothesis. "," This error, to understand the complex hypothesis of the structure of nucleic acid is in effect, and to a certain extent of nucleic acid functions of people. People think that although the nucleic acid exists in important structure -- the nucleus, but its structure, it is hard to imagine that it is too simple genetic process in what role.
Protein found in 30 years earlier than the nucleic acid, is developing rapidly. In the 20th century, when the 20 amino acids in the protein have 12 was found, to all that was in 1940.
In 1902, German chemist's fee from between amino acids proposed by peptide chains and protein linking the theory, 1917 he was synthesized by 15 glycine and 3 LiangAnSuan consist of 18 peptide chains of. So, some scientists, probably in genetic. If the nucleic acid in genetic, must be together with the proteins in the nucleoprotein. Therefore, when nature common tend to think that protein is the carrier of genetic information.
In 1928, American scientists grievous (1941) in 1877 - a JiaMo, strong and a toxic JiaMo without toxic weak ShuangQiuJun pneumonia, the mouse experiment. He has to kill bacteria in high after the pod and live together with the pod bacteria, the mice who note that he died, mouse soon onset of blood from his mice had lived there pod germs. This shows that bacteria from death without pod of bacteria have gained in any pod, no matter for a pod into pod. This hypothesis is correct? Grievous in test tubes, the experiments have found dead and live without beauty in a test tube simultaneously pod bacteria, fungi all become without pod, and found there pod that bacteria grow without pod protein pod is dead are left in the shell pod bacteria in the nucleic acid (because of the heat, pod and no nucleic acid). Grievous said the nucleic acid as "transformation factor".
In 1944, the United States bacteriologist Avery (1877-1955) from a beautiful bacteria isolated activity, "and" transformation factor for this matter do inspection protein, the test whether there is negative, and prove "transformation factor" is the DNA. But this is widely acknowledged that no doubt, people can cleanse protein of technology, has transformed the residue of protein.
American scientists del cloth luc (1906-1981) found in Avery phage group. Because they came in electronic microscope phage form and enter the growth of e. coli. Phages are bacteria for the host cell in the form of a virus that individuals with electron microscope, only to see them. It is like a small tadpoles, external is composed by protein membrane and head of the tail scabbard, head, tail DNA contains the scabbard is tail, substrate and small hook. When the phage infect escherichia coli, the tail end in the membrane of bacteria, and then it will all the body to bacterial DNA cells injection, protein to remain in bacteria outside shell, no cells what effect. After the cells into bacteria, using bacteria phage DNA synthesis of the material of phage quickly and DNA and protein, with the original copy out many phage size shape like a new phage, until the bacteria was completely, leaving only these phages died of bacteria, to infect other bacteria.
In 1952, phage group members hirsch (1908) and his students to chase with advanced technology, do 13c-substrate phage infect escherichia coli experiments. He put the e. coli T2), the nucleic acid 32P 35S on protein shell markers. With the first mark e. coli, phage T2 infection and are isolated, results of phage 35S will take mark e. coli outside shell stay inside, only with the phage 32P mark's note meropenem all the nucleic acid, and in e. coli successfully conducted within the phage reproduction. The experiment proved that DNA has passed, and the function of the genetic information from the DNA protein synthesis of instructions. The results immediately accepted for academic.
Almost at the same time, Austria biochemists chagas - to Cardiff (1905) the four bases of nucleic acids content determination of fruit. Under the influence of the work in Avery, he thinks that if the creature is different because of different DNA, the structure of DNA is complex, or to the biological diversity. Therefore, he told the "four lieven nucleotide hypothesis" created doubts. In 1948-1952 4 years, he took advantage of The Times more accurate than lieven paper chromatography separation four bases, uv absorption spectrum do quantitative analysis, multiple repeated experiments, finally came to a different result. Levin Experimental results show that, in the DNA molecules in the us and thymine Piao the total number of molecules, said A Piao glands and thymine * T equal Piao bird said G and cytosine equal. C, Explain the DNA molecule with T, G, A base pairs of existence with C is negative, and four nucleotide hypothesis ", "and to explore the DNA molecule structure provides important clues and basis.
On April 25, 1953, Britain's nature magazine published the Watson and crick in Britain at the university of Cambridge research achievements of cooperation of the double helix structure of DNA molecules, and this result later model since the 20th century as the greatest discovery of biology, marks the birth of molecular biology.
Watson (1928) in a middle school is a very clever boy, at the age of 15 entered university of Chicago. At that time, because the early allowed a human, experimental education plan from aspects of chance Watson studying biological science course completely. In college, Watson in genetics, though few aspects have a formal training, but since starting the read your life? What is the physical appearance, living cells newcomb, prompting him to find the secret of genes. He is so long, all contribute to the ideas of others with good enrich himself. As long as there is convenient conditions, don't force yourself to learn the new field, can get the knowledge needed. Dr. Watson 22 degrees, and obtained by studying postdoctoral fellow to Europe. In order to fully clear a virus gene chemical structure, to study chemistry lab Copenhagen, Denmark. He once and mentor to Italy in a biological macromolecules napoli have chance to listen to English conference, physical biologists wilkings showed (1916) speech -- see wilkings showed pictures of DNAX ray diffraction. Since then, the structure of DNA for loose in the key ideas in the mind of Watson claims. Where can I learn analysis X-ray diffraction figure? So he again to the university of Cambridge's laboratory study, Calvin don&apost know in this period. Watson post-lava creek
Crick (MCA) a 2004 in 1916, scientific accomplishment of passion in 1937, graduated from London university. In 1946, he read the life is? - living cells, the physical appearance of the physics knowledge for determination of biology research, the biology. In 1947, he started a graduate study, 1949, he used together with peruzzi form X-ray protein molecules structure, technical research and so on, met Watson. At age 12 large than Watson post-lava creek, also have doctoral degree. But they talked about is speculative, Watson was here could find a more important than knowing DNA protein, it's a great honor to. While he was in contact with Watson and crick among the people are the most intelligent one. They talk at least for several hours everyday, discusses the academic problems. Two complement each other and criticism of inspiration inspired. They say part of the solution is open genetic structure of DNA molecule mysteries of the key. Only by precise X-ray diffraction data, can quickly out of the structure of DNA. In order to get information, crick DNAX ray diffraction, please come to Cambridge wilkings showed the weekend. In the conversation wilkings showed accepted the spiral structure of DNA is, also spoke of his partners franklin (1920, female) and a 1958 laboratory scientists, the structure of DNA in scratching the model. In 1951, November to 1953 on April 18 months, Watson and crick wilkings showed, with a few times between franklin's academic exchanges is important.
In 1951, November, Watson heard about the structure of DNA franklin after the detailed report, has inspired, crystal structure analysis knowledge Watson and crick soon realized, to establish DNA structure model of others, the analysis of the data. They soon put forward three strands of DNA in a spiral structure. At the end, they please 1951 wilkings showed and franklin to discuss the model, the DNA of Benjamin Franklin pointed out that they were less water, so the first half well established model has failed.
One day, Watson and to the lab, wilkings showed wilkings showed a recently took out of Benjamin Franklin "B type" DNA X-ray diffraction photos. Watson A photos, immediately got excited and heartbeat accelerate, because this is the "image than before A type" as A much simpler, see "B" X-ray diffraction by simple calculation, photos, DNA molecules can be determined in A number of nucleotide chain more.
Crick please help calculation, the results show that the mathematician has attracted the source said the trend pyrimidines. According to the results, and they find Randolph obtained from the nucleic acid with two of us and two thymine Piao two equal results, the concept of base pairing.
They bitterly about four bases of sequence, again and again in the paper bases on the picture, playing with model, and were put to overthrow assumptions, and his assumptions.
Watson and crick (left), Watson and in his own ideas, he put the model base eagerness moved to remove the possibility for various pairing. Suddenly, he found the glands connected by two hydrogen said a thymine bases for belt to and from three hydrogen Piao bird said a connection to the same cytosine, so the shape of the spirit. The number of us because Piao why and thymine exactly the same number of this mystery shall be solved. Check and law at Cardiff with DNA double helix structure into the inevitable result. Therefore, how to as a template synthesis a complementary sequence of chain will base envisioned. Then, two chains skeleton must be the opposite direction.
After Watson and crick continuous work, tension soon finished metal model of DNA. From this model, DNA consists of two nucleotides chains, their central axis in the opposite direction along with each other, like intertwined in a spiral staircase armrest, is more than two sides of sugar a nucleotide chain of phosphorus gene alternately, that is the skeleton step. Due to the lack of accurate information, they also X-ray not judge model is completely correct.
Benjamin Franklin wilkings showed the scientific method is based on the model prediction out and X-ray diffraction experiment data of a serious. They call again had wilkings showed. Within two days, when franklin and wilkings showed with X-ray data analysis of the double helix structure model is proved correct, and wrote two experimental report published in the British journal nature. In 1962, Watson and crick and wilkings showed won the Nobel Prize for physiology and medicine, and for cancer franklin died in 1958 and was awarded the award.
In the 1930s, the Swedish scientists is that the asymmetry of DNA. The second world war by electron microscopy, the determination of the diameter of the DNA molecules out about 2nm.
DNA double helix structure was discovered, greatly shook the academia, inspired people's thoughts. From then on, people immediately to the center of genetics of molecular biology research. First is around four bases coding permutation how to express 20 amino acids centers for experimental study. In 1967, the genetic code are all cracked, gene and so on in the DNA molecule level of new concepts. It shows that the gene is actually a segment of DNA molecules, biological characters is to control the genetic material structure and functions. In this unit of many pieces of nucleotide, but not in any arrangement has implications of the sequence of codes. Certain structure of DNA, can control the protein synthesis of corresponding structures. Protein is an important component of living organisms, biological characters is mainly embodied by protein. Therefore, the control of genes is through the characters of protein synthesis of DNA control. Based on the genetic engineering, after fermentation engineering, enzyme engineering, etc, these creatures protein engineering technology development will make people using biological rules for the benefit of humanity. The development of modern biology, more and more shows its rise to lead to the subject.