Prof. Duluman E.K.
Nobel laureate Francis Crick and atheism
(To the 50th anniversary of the discovery of DNA)
If religions revealed
have revealed anything
it is that they
are usually wrong.
(If the religions of Revelation ,
something is being discovered there,
then these revelations usually
turn out to be deceitful)
Francis Crick
Francis Creek
In 2003, the world scientific community celebrated the 50th anniversary of the discovery of the structure of DNA. Russian Academy Sciences dedicated the entire sixth issue of “BULLETIN OF THE RUSSIAN ACADEMY OF SCIENCES” for 2003 to this significant event, festively calling it: TO THE 50TH ANNIVERSARY OF THE DISCOVERY OF THE STRUCTURE OF DNA.
Our leading and world-famous academicians delivered detailed analytical and informational articles: L.L. Kiselev,"Anniversary of the most important molecule"; E. D. Sverdlov,"The Great Discovery: Revolution, Canonization, Dogma and Heresy"; V. L. Karpov,"DNA, chromatin, histone code". By clicking on the title of these articles, you will get the opportunity to get acquainted with full texts their authors.
Academician L.L. Kiselev writes:
Watson and Crick were awarded the Nobel Prize in 1962 for their discovery of the structure of DNA.
After reading the articles in the academic journal, I remembered the atheist articles I had read earlier and the statements of Francis Harry Compton Crick ( Francis Harry Compton Crick) and his biography under an intriguing, if not strange, title: “ What Mad Pursuit», which can be translated as " What is a crazy person looking for?" It can be translated differently, since the word “mad” can mean “biased”, “selfless”, “in love”, and “mad”, and the word “Pursuit” - “pursue”, “convince”, “abide” in search." However, when reading Crick’s autobiography, one gets the impression that he used the word “mad” in response to the Biblical charge of an atheist with madness: “A fool says in his heart: There is no God” (Psalm 13:1; 52:2). In this place English translations The Bible of a madman is called “mad.”
In his autobiography " What Mad Pursuit» There is a special chapter that Crick called: “How I Got Inclined Towards Atheism.” We do not have the opportunity to retell all the interesting and unique thoughts of the great scientist about the atheistic and religious worldview. We will give only three of the most representative, in our opinion, quotes from this greatest scientist and convinced atheist..
« Mere knowledge of the true age of the earth, as convincingly demonstrated by geological deposits, fossils of plants and animals, does not allow the intelligent mind to believe literally, like religious fundamentalists, in everything that is written in the Bible. And if some messages of the Bible are clearly false, then why are others biblical stories must be taken as truth?»
« Christian religious beliefs during their formation, they may have responded not only to the imagination of believers, but also to the level of knowledge of that era. But, as unfortunate as it was, subsequent scientific discoveries not only decisively refuted Christian beliefs, but also put them in an unsightly light. What could be more stupid than to base the way of life of modern man entirely on erroneous ideas only on the basis that they, these ideas, were once considered true? And what could be more important than to find your true place in the Universe by eliminating, one by one, these vicious remnants of earlier beliefs? But it is still clear that a number of secrets are still waiting to be discovered. scientific explanation. Until they are explained, they can harbor all sorts of religious superstitions.
For me, a matter of paramount importance was the desire to identify still unknown areas of knowledge in biology, to achieve their true scientific understanding. Only in this way could religious beliefs be confirmed or refuted».
* * *
« The astonishing hypothesis is that your joys and sorrows, your memories and ambitions, your sense of self and free will are all in fact nothing more than the manifestation of the activity of a huge complex of nerve cells and their associated molecules. As Lewis Carroll's Alice would put it, you're just a bag of neurons. ».
"Revelation Religions" are Judaism, Christianity and Islam, which believe that the content of their beliefs is revealed to them by God in the text of the Bible...
(English) FrancisCrick was born, June 8 in Northampton, England; died aged 88
The beginning of this story can be taken as a joke. "And we just discovered the secret of life!" - said one of the two men who entered the Cambridge Eagle pub exactly 50 years ago - February 28, 1953. And these people who worked in a laboratory nearby were not exaggerating at all. One of them was named Francis Crick, and the other was James Watson.
Watson and Crick discovered the structure of deoxyribonucleic acid (DNA), a substance that contains all hereditary information. A few months after the historic announcement in the pub, a cautious publication of the work of two researchers came out in the journal Nature (Watson J.D., Crick F.H.C. Molecular structure of nucleic acids // Nature. 1953. V. 171. P. 738-740). The article ended with the suggestion that the discovery of the structure of DNA could explain the mechanisms by which genetic material is copied.
By the fifties, it was known that DNA is a large molecule that consists of thousands of small molecules connected to each other in a line of four different types– nucleotides. Scientists also knew that it was DNA that was responsible for storing and inheriting genetic information, similar to text written in a four-letter alphabet. The spatial structure of this molecule and the mechanisms by which DNA is inherited from cell to cell and from organism to organism remained unknown.
In 1948, Linus Pauling discovered the spatial structure of other macromolecules—proteins. Bedridden by jade, Pauling spent several hours folding paper with which he tried to model the configuration of a protein molecule, and created a model of a structure called the “alpha helix.”
According to Watson, after this discovery, the hypothesis about the helical structure of DNA became popular in their laboratory. Watson and Crick collaborated with leading experts in X-ray diffraction analysis, and Crick was able to almost accurately detect signs of a spiral in images obtained in this way.
Pauling also believed that DNA is a helix, moreover, consisting of three strands. However, he could not explain either the nature of such a structure or the mechanisms of DNA self-duplication for transmission to daughter cells.
The discovery of the double-stranded structure occurred after Maurice Wilkins secretly showed Watson and Crick an X-ray of a DNA molecule taken by his collaborator Rosalind Franklin. In this image, they clearly recognized the signs of a spiral and headed to the laboratory to check everything on a three-dimensional model.
In the laboratory it turned out that the workshop did not supply the necessary stereo models metal plates, and Watson cut out four types of nucleotide models from cardboard - guanine (G), cytosine (C), thymine (T) and adenine (A) - and began to lay them out on the table. And then he discovered that adenine combines with thymine, and guanine with cytosine according to the “key-lock” principle. This is exactly how the two strands of the DNA helix are connected to each other, that is, opposite the thymine from one strand there will always be adenine from the other, and nothing else.
This arrangement made it possible to explain the mechanisms of DNA copying: two strands of the helix diverge, and to each of them an exact copy of its former “partner” in the helix is added from nucleotides. Using the same principle as printing a positive from a negative in a photograph.
The fate of Rosalind Franklin was very sad. Wilkins called his subordinate exclusively “bluestocking” and was in constant conflict with her. Although Franklin did not support the hypothesis about the helical structure of DNA, it was her photographs that played a role in decisive role in the discovery of Watson and Crick. And maybe Pauling would have been awarded the fourth Nobel Prize, if only he could see these pictures before the British researchers.
Rosalind did not live to see the prize that Wilkins, Watson and Crick received. She died of cancer in 1958.
It is obvious that the discovery of the spatial structure of DNA made a revolution in the world of science and entailed a whole series of new discoveries, without which it is impossible to imagine not only modern science, but also modern life generally
In the sixties of the last century, Watson and Crick's assumption about the mechanism of DNA replication (doubling) was completely confirmed. In addition, it was shown that a special protein, DNA polymerase, takes part in this process.
Around the same time, another important discovery was made - genetic code. As mentioned above, DNA contains information about everything that is inherited, including linear structure every protein in the body. Proteins, like DNA, are long molecular chains of amino acids. There are 20 of these amino acids. Accordingly, it was unclear how the “language” of DNA, consisting of a four-letter alphabet, is translated into the “language” of proteins, where 20 “letters” are used.
It turned out that the combination of three DNA nucleotides clearly corresponds to one of the 20 amino acids. And thus, what is “written” on DNA is unambiguously translated into protein.
In the seventies, two more important methods appeared, based on the discovery of Watson and Crick. This is sequencing and obtaining recombinant DNA. Sequencing allows you to “read” the sequence of nucleotides in DNA. It is on this method that the entire Human Genome program is based.
Obtaining recombinant DNA is otherwise called molecular cloning. The essence of this method is that a fragment containing a specific gene is inserted into a DNA molecule. In this way, for example, bacteria are obtained that contain the gene for human insulin. Insulin obtained in this way is called recombinant. All “genetically modified products” are created using the same method.
Paradoxically, reproductive cloning, which everyone is talking about now, appeared before the structure of DNA was discovered. It is clear that now scientists conducting such experiments are actively using the results of the discovery of Watson and Crick. But, initially, the method was not based on it.
The next important step in science was the development of the polymerase chain reaction in the eighties. This technology is used to quickly “reproduce” the desired DNA fragment and has already found many applications in science, medicine and technology. In medicine, PCR is used to make quick and accurate diagnostics. viral diseases. If the mass of DNA obtained from a patient’s analysis contains genes brought by the virus, even in minimal quantities, then using PCR it is possible to “multiply” them and then easily identify them.
In addition to the fact that the discovery of Watson and Crick became the basis for many scientific studies, including the famous Human Genome Project, the DNA molecule left its mark in modern painting, cinema, and architecture.
James Dewey Watson - American molecular biologist, geneticist and zoologist; He is best known for his participation in the discovery of the structure of DNA in 1953. Winner of the Nobel Prize in Physiology or Medicine.
After successfully graduating from the University of Chicago and Indiana University, Watson spent some time doing chemistry research with biochemist Herman Kalckar in Copenhagen. He later moved to the Cavendish Laboratory at the University of Cambridge, where he first met his future colleague and comrade Francis Crick.
Watson and Crick came up with the idea of a DNA double helix in mid-March 1953, while studying experimental data collected by Rosalind Franklin and Maurice Wilkins. The discovery was announced by Sir Lawrence Bragg, director of the Cavendish Laboratory; This happened at a Belgian scientific conference on April 8, 1953. The important statement, however, was not actually noticed by the press. On April 25, 1953, an article about the discovery was published in scientific journal"Nature". Other biological scientists and a number of Nobel laureates quickly appreciated the monumentality of the discovery; some even called it the greatest scientific discovery 20th century.
In 1962, Watson, Crick and Wilkins received the Nobel Prize in Physiology or Medicine for their discovery. The fourth participant in the project, Rosalind Franklin, died in 1958 and, as a result, could no longer qualify for the prize. Watson was also awarded a monument at the American Museum of Natural History in New York for his discovery; since such monuments are erected only in honor of American scientists, Crick and Wilkins were left without monuments.
Watson is still considered one of the greatest scientists in history; however, many people openly disliked him as a person. James Watson has been involved in quite high-profile scandals several times; one of them was directly related to his work - the fact is that while working on the DNA model, Watson and Crick used data obtained by Rosalind Franklin without her permission. The scientists worked quite actively with Franklin's partner, Wilkins; Rosalind herself, quite possibly, might not have known until the end of her life how important the role her experiments played in understanding the structure of DNA.
From 1956 to 1976, Watson worked at Harvard's biology department; During this period he was interested mainly in molecular biology.
In 1968, Watson received a position as director of the Cold Spring Harbor Laboratory in Long Island, New York; Thanks to his efforts, the quality level in the laboratory has significantly increased research work, and financing has improved markedly. Watson himself was primarily involved in cancer research during this period; Along the way, he made the laboratory under his control one of the best centers of molecular biology in the world.
In 1994, Watson became president of the research center, and in 2004 - rector; in 2007, he left his position after making rather unpopular statements about the existence of a connection between intelligence level and origin.
Best of the day
Visited:6279 |
Igor Khiryak. Black liquidator of the Chernobyl accident Visited:248 |
"The Diary of Anne Frank" denouncing the Nazis |
The discovery of the duplicated DNA helix proved to be a watershed moment in biology. It was made by the Englishman Francis Crick and the American James Watson. In 1962, scientists were awarded the Nobel Prize.
They are considered among the most smart people on the planet. Crick made many discoveries in various fields, not limited to genetics. Watson earned himself notoriety with a number of statements, but this characterizes him more as an extraordinary person.
Childhood
Francis Crick was born in 1916 in Northampton, England. His father was a successful businessman and owned a shoe factory. He went to a regular high school. After the war, the family's income decreased significantly, the head decided to move the family to London. Francis graduated from Mill Hill School, where he was interested in mathematics, physics and chemistry. He later studied at University College London and was recognized as a Bachelor of Science.
Then his future colleague, James Watson, was born on another continent. Since childhood, he was different from ordinary children; even then, James was predicted to have a bright future. He was born in Chicago in 1928. His parents surrounded him with love and joy.
The teacher in the first grade noted that his intelligence was inappropriate for his age. After 3rd grade, he took part in an intellectual quiz for children on the radio. Watson showed amazing abilities. Later he would be invited to the four-year University of Chicago, where he would become interested in ornithology. Having a bachelor's degree, the young man decides to continue his studies at the University of Bloomington in Indiana.
Interest in science
At Indiana University, Watson studies genetics and comes to the attention of the biologist Salvador Lauria and the brilliant geneticist J. Moeller. The collaboration resulted in a dissertation on the effect of X-rays on bacteria and viruses. After a brilliant defense, James Watson became a Doctor of Science.
Further research on bacteriophages will take place in distant Denmark – the University of Copenhagen. The scientist is actively working on compiling a DNA model and studying its properties. His colleague is the talented biochemist Herman Kalkar. However, a fateful meeting with Francis Crick will take place at the University of Cambridge. An aspiring scientist, Watson, who is only 23 years old, will invite Francis to his laboratory to work together.
Before World War II, Crick studied the viscosity of water in various states. Later he had to work for the Navy Department - developing mines. The turning point will be reading the book by E. Schrödinger. The author's ideas pushed Francis to study biology. Since 1947 he has worked in a Cambridge laboratory studying X-ray diffraction, organic chemistry and biology. Its leader was Max Perutz, who studies the structure of proteins. Crick develops an interest in defining chemical basis genetic code.
DNA decoding
In the spring of 1951, a symposium was held in Naples, where James met the English scientist Maurice Wilkins and researcher Rosalyn Franklin, who were also conducting DNA analysis. They determined that the cell structure is similar to spiral staircase- It has double form spirals. Their experimental data prompted Watson and Crick to conduct further research. They decide to determine the composition of nucleic acids and seek the necessary funding - a grant from the National Society for the Study of Infantile Paralysis.
James Watson In 1953, they would inform the world about the structure of DNA and present a completed model of the molecule.
In just 8 months, two brilliant scientists will summarize the results of their experiments with the available data. In a month, a three-dimensional DNA model will be made from balls and cardboard.
The discovery was announced by Lawrence Bragg, director of the Cavendish Laboratory, at a Belgian conference on April 8. But the importance of the discovery was not immediately recognized. Only on April 25, after the publication of an article in the scientific journal Nature, biologists and other laureates truly appreciated the value of new knowledge. The event was considered the greatest discovery of the century.
In 1962, the Englishmen Wilkins and Crick and the American Watson were nominated for the Nobel Prize in Medicine. Unfortunately, Rosalind Franklin died 4 years ago and was not among the contenders. There was a huge scandal about this, since the model used data from Franklin’s experiments, although she did not give official permission. Crick and Watson worked closely with her partner Wilkins, and Rosalind herself did not learn the importance of her experiments for medicine until the end of her life.
A monument was erected to Watson for his discovery in New York. Wilkins and Crick were not given this honor because they did not have American citizenship.
Career
After the discovery of the structure of DNA, Watson and Crick diverged. James became a senior member of the biology department at the University of California, and later became a professor. In 1969, he was offered to head the Long Island Laboratory of Molecular Biology. The scientist refuses to work at Harvard, where he has worked since 1956. He will devote the rest of his life to neurobiology, studying the influence of viruses and DNA on cancer. Under the leadership of the scientist, the laboratory reached a new level of research quality, and its funding increased significantly. Gold Spring Harbor has become the world's leading center for the study of molecular biology. From 1988 to 1992, Watson was actively involved in a number of projects to study the human genome.
After international recognition, Crick became the head of a biological laboratory in Cambridge. In 1977 he moved to San Diego, California, to study the mechanisms of dreams and vision.
Francis Creek In 1983, with the mathematician Gr. Mitchison, he suggested: dreams are the brain’s ability to free itself from useless and excessive associations that were accumulated during the day. Scientists have called dreams a way to prevent overload of the nervous system.
In 1981, Francis Crick’s book “Life as It Is: Its Origin and Nature” was published, where the author speculates about the origin of life on Earth. According to his version, the first inhabitants on the planet were microorganisms from other space objects. This explains the similarity of the genetic code of all living objects. The scientist died in 2004 from oncology. He was cremated and his ashes were scattered over Pacific Ocean.
Francis Creek In 2004, Watson became rector, but in 2007 he had to resign from this position for speaking about the genetic connection between origin (race) and level of intelligence. The scientist loves to comment provocatively and insultingly on the work of his colleagues, and Franklin was no exception. Some statements were perceived as attacks against obese people and homosexuals.
In 2007, Watson released his autobiography, Avoid Boring. In 2008, he gave a public lecture at Moscow State University. Watson is called the first person with a completely deciphered genome. The scientist is currently working to find genes responsible for mental illness.
Crick and Watson opened up new possibilities for the development of medicine. Overestimate their importance scientific activity impossible.
The relevance and reliability of information is important to us. If you find an error or inaccuracy, please let us know. Highlight the error and press the keyboard shortcut Ctrl+Enter .
The DNA double helix is 50 years old!
On Saturday February 28, 1953, two young scientists, J. Watson and F. Crick, in a small diner Eagle in Cambridge announced to a lunch crowd that they had discovered the secret of life. Many years later, Odile, F. Crick's wife, said that she, of course, did not believe him: when he came home, he often stated something like that, but then it turned out that this was a mistake. This time there was no mistake, and with this statement a revolution in biology began that continues to this day.
April 25, 1953 in the magazine Nature three articles appeared on the structure of nucleic acids. In one of them, written by J. Watson and F. Crick, the structure of the DNA molecule was proposed in the form of a double helix. The other two, written by M. Wilkins, A. Stokes, G. Wilson, R. Franklin and R. Gosling, presented experimental data confirming the helical structure of DNA molecules. The story of the discovery of the double helix of DNA resembles an adventure novel and deserves at least a brief summary.
The most important ideas about the chemical nature of genes and the matrix principle of their reproduction were first clearly formulated in 1927 by N.K. Koltsov (1872–1940). His student N.V. Timofeev-Resovsky (1900–1981) took these ideas and developed them as the principle of convariant reduplication of genetic material. German physicist Max Delbrück (1906–1981; Nobel Prize 1969), active in the mid-1930s. at the Kaiser Wilhelm Institute of Chemistry in Berlin, under the influence of Timofeev-Resovsky, he became so interested in biology that he quit physics and became a biologist.
For a long time, in full accordance with Engels' definition of life, biologists believed that the hereditary substance was some special proteins. Nobody thought that nucleic acids could have anything to do with genes - they seemed too simple. This continued until 1944, when a discovery was made that radically changed the entire further development of biology.
This year, an article by Oswald Avery, Colin McLeod and McLean McCarthy was published showing that in pneumococci, heritable properties are transferred from one bacteria to another using pure DNA, i.e. DNA is the substance of heredity. McCarthy and Avery then showed that treating DNA with a DNA-digesting enzyme (DNase) caused it to lose gene properties. It is still unclear why this discovery was not awarded the Nobel Prize.
Shortly before, in 1940, L. Pauling (1901–1994; Nobel Prizes 1954 and 1962) and M. Delbrück developed the concept of molecular complementarity in antigen-antibody reactions. In those same years, Pauling and R. Corey showed that polypeptide chains can form helical structures, and somewhat later, in 1951, Pauling developed a theory that made it possible to predict the types of x-ray patterns for various helical structures.
After the discovery of Avery et al., although it did not convince proponents of the protein gene theory, it became clear that it was necessary to determine the structure of DNA. Among those who understood the importance of DNA for biology, a race for results began, accompanied by fierce competition.
X-ray machine used in the 1940s. for studying the crystal structure of amino acids and peptides
In 1947–1950 Based on numerous experiments, E. Chargaff established a rule of correspondence between nucleotides in DNA: the numbers of purine and pyrimidine bases are the same, and the number of adenine bases is equal to the number of thymine bases, and the number of guanine bases is equal to the number of cytosine bases.
The first structural works (S. Ferberg, 1949, 1952) showed that DNA has a helical structure. Having extensive experience in determining the structure of proteins from X-ray diffraction patterns, Pauling undoubtedly could have quickly solved the problem of the structure of DNA if he had had any decent X-ray diffraction patterns. However, there were none, and from those he managed to obtain, he was unable to make a clear choice in favor of one of the possible structures. As a result, in his haste to publish the result, Pauling chose the wrong option: in a paper published in early 1953, he proposed a structure in the form of a three-stranded helix, in which the phosphate residues form a rigid core, and the nitrogenous bases are located on the periphery.
Many years later, recalling the story of the discovery of the structure of DNA, Watson remarked that "Linus [Pauling] did not deserve to guess correct solution. He didn't read the articles or talk to anyone. Moreover, he even forgot his own paper with Delbrück, which talks about the complementarity of gene replication. He thought he could figure out the structure just because he was so smart.”
When Watson and Crick began work on the structure of DNA, much was already known. It remained to obtain reliable X-ray structural data and interpret them on the basis of the information already available at that time. How all this happened is well described in the famous book “The Double Helix” by J. Watson, although many of the facts in it are presented very subjectively.
J. Watson and F. Crick on the verge of a great discovery
Of course, in order to build a double helix model, extensive knowledge and intuition were needed. But without the coincidence of several coincidences, the model could have appeared several months later, and its authors could have been other scientists. Here are some examples.
Rosalind Franklin (1920–1958), who worked with M. Wilkins (Nobel Prize 1962) at King's College (London), obtained the highest quality X-ray diffraction patterns of DNA. But this work interested her little; she considered it routine and was in no hurry to draw conclusions. This was facilitated by her bad relationship with Wilkins.
At the very beginning of 1953, Wilkins, without the knowledge of R. Franklin, showed Watson her radiographs. In addition, in February of the same year, Max Perutz showed Watson and Crick the annual report of the Medical Research Council, reviewing the work of all leading employees, including R. Franklin. This was enough for F. Crick and J. Watson to understand how the DNA molecule should be structured.
X-ray of DNA obtained by R. Franklin
In an article by Wilkins et al., published in the same issue Nature The same as the paper by Watson and Crick, it is shown that, judging by X-ray diffraction patterns, the structure of DNA from different sources is approximately the same and is a helix in which the nitrogenous bases are located on the inside and the phosphate residues on the outside.
The article by R. Franklin (with her student R. Gosling) was written in February 1953. Already in the initial version of the article, she described the structure of DNA in the form of two coaxial helices shifted relative to each other along the axis with nitrogenous bases inside and phosphates outside. According to her data, the pitch of the DNA helix in form B (i.e., at a relative humidity of >70%) was 3.4 nm, and there were 10 nucleotides per turn. Unlike Watson and Crick, Franklin did not build models. For her DNA was nothing more interesting object research than coal and carbon, which she was engaged in in France before coming to King's College.
Having learned about the Watson-Crick model, she added by hand in the final version of the article: “Thus, our general ideas do not contradict the Watson-Crick model given in the previous article.” Which is not surprising, because... this model was based on her experimental data. But neither Watson nor Crick, despite the most friendly relations with R. Franklin, ever told her what they repeated publicly many times years after her death - that without her data they would never have been able to build their model.
R. Franklin (far left) at a meeting with colleagues in Paris
R. Franklin died of cancer in 1958. Many believe that if she had lived until 1962, the Nobel Committee would have had to break its strict rules and award the prize to not three, but four scientists. In recognition of her and Wilkins' achievements, one of the buildings at King's College was named Franklin-Wilkins, forever linking the names of people who barely spoke to each other.
When reading the article by Watson and Crick (shown below), one is surprised by its small volume and lapidary style. The authors were well aware of the significance of their discovery and, nevertheless, limited themselves to only a description of the model and a brief indication that “from the postulated ... specific formation of pairs, a possible mechanism for copying genetic material immediately follows.” The model itself seemed to be taken out of thin air - there is no indication of how it was obtained. Its structural characteristics are not given, with the exception of the pitch and number of nucleotides per pitch of the helix. The formation of pairs is also not clearly described, because At that time, two systems were used for numbering the atoms in pyrimidines. The article is illustrated with only one drawing made by F. Crick's wife. However, for ordinary biologists, the articles of Wilkins and Franklin, overloaded with crystallographic data, were difficult to understand, but the article of Watson and Crick was understood by everyone.
Later, both Watson and Crick admitted that they were simply afraid to present all the details in the first article. This was done in a second paper entitled "Genetic Consequences from the Structure of DNA" and published in Nature May 30 of the same year. It provides the rationale for the model, all the dimensions and details of the DNA structure, patterns of chain formation and base pairing, and discusses various implications for genetics. The nature and tone of the presentation indicate that the authors are quite confident in their correctness and the importance of their discovery. True, they connected the G–C pair with only two hydrogen bonds, but a year later in a methodological article they indicated that three bonds were possible. Soon Pauling confirmed this with calculations.
Watson and Crick's discovery showed that genetic information is written in DNA in a four-letter alphabet. But it took another 20 years to learn to read it. The question immediately arose about what the genetic code should be. The answer to this question was proposed in 1954 by theoretical physicist G.A. Gamow*: information in DNA is encoded by triplets of nucleotides - codons. This was confirmed experimentally in 1961 by F. Crick and S. Brenner. Then, within 3–4 years, in the works of M. Nirenberg (Nobel Prize 1965), S. Ochoa (Nobel Prize 1959), H. Korana (Nobel Prize 1965) and others, the correspondence between codons and amino acids.
In the mid-1970s. F. Sanger (b. 1918; Nobel Prizes 1958 and 1980), also working at Cambridge, developed a method for determining nucleotide sequences in DNA. Sanger used it to determine the sequence of the 5386 bases that make up the genome of bacteriophage jX174. However, the genome of this phage is a rare exception: it is single-stranded DNA.
The present era of genomes began in May 1995, when J.K. Venter announced the deciphering of the first genome of a single-celled organism - a bacterium. Haemophilus influenzae. The genomes of about 100 different organisms have now been deciphered.
Until recently, scientists thought that everything in a cell was determined by the sequence of bases in DNA, but life is apparently much more complex.
It is now well known that DNA often has a shape other than the Watson–Crick double helix. More than 20 years ago, the so-called Z-helical structure of DNA was discovered in laboratory experiments. This is also a double helix, but twisted in the opposite direction compared to the classical structure. Until recently, it was believed that Z-DNA had nothing to do with living organisms, but recently a group of researchers from the National Heart, Lung, and Blood Institutes (USA) discovered that one of the genes of the immune system is activated only when part of its regulatory sequence goes into Z-shape. It is now assumed that the temporary formation of the Z-form may be a necessary link in the regulation of the expression of many genes. In some cases, viral proteins have been found to bind to Z-DNA and lead to cell damage.
In addition to helical structures, DNA can form the well-known twisted rings in prokaryotes and some viruses.
Last year, S. Nidle of the Institute of Cancer Research (London) discovered that the irregular ends of chromosomes - telomeres, which are single strands of DNA - can fold into very regular structures, resembling a propeller). Similar structures were found in other regions of chromosomes and were called G-quadruplexes, since they are formed by regions of DNA rich in guanine.
Apparently, such structures help stabilize the DNA sections where they are formed. One of the G-quadruplexes was found directly next to the gene c-MYC, the activation of which causes cancer. In this case, it can prevent gene activator proteins from binding to DNA, and researchers have already begun searching for drugs that stabilize the structure of G-quadruplexes, in the hope that they will help fight cancer.
IN last years not only the ability of DNA molecules to form structures other than the classical double helix was discovered. To the surprise of scientists, DNA molecules in the cell nucleus are in continuous motion, as if “dancing.”
It has long been known that DNA forms complexes with histone proteins in the nucleus with protamine in sperm. However, these complexes were considered strong and static. Using modern video technology, it was possible to film the dynamics of these complexes in real time. It turns out that DNA molecules constantly form fleeting connections with each other and with various proteins that hover around DNA like flies. Some proteins move so fast that they travel from one side of the nucleus to the other in 5 seconds. Even histone H1, which is most tightly bound to the DNA molecule, dissociates and reconnects with it every minute. This inconsistency of connections helps the cell regulate the activity of its genes - DNA constantly checks for the presence of transcription factors and other regulatory proteins in its environment.
The nucleus, which was considered a rather static formation - a repository of genetic information - actually lives a vibrant life, and the well-being of the cell largely depends on the choreography of its components. Some human diseases may be caused by disruptions in the coordination of these molecular dances.
Obviously, with such an organization of the life of the nucleus, its different parts are unequal - the most active “dancers” should be closer to the center, and the least active ones should be closer to the walls. And so it turned out. For example, in humans, chromosome 18, which has only a few active genes, is always located near the border of the nucleus, and chromosome 19, full of active genes, is always near its center. Moreover, the movement of chromatin and chromosomes, and even simply the relative position of chromosomes, apparently affects the activity of their genes. Thus, the close location of chromosomes 12, 14 and 15 in the nuclei of mouse lymphoma cells is considered a factor contributing to the transformation of the cell into a cancerous one.
The past half century in biology became the era of DNA - in the 1960s. the genetic code was deciphered in the 1970s. Recombinant DNA was obtained and sequencing methods were developed in the 1980s. The polymerase chain reaction (PCR) was developed, and the Human Genome Project was launched in 1990. One of Watson's friends and colleagues, W. Gilbert, believes that traditional molecular biology is dead - now everything can be found out by studying genomes.
F. Crick among the staff of the Laboratory of Molecular Biology in Cambridge
Now, looking through the papers of Watson and Crick 50 years ago, one is surprised how many of the assumptions turned out to be true or close to the truth - after all, they had almost no experimental data. As for the authors themselves, both scientists are celebrating the fiftieth anniversary of the discovery of the structure of DNA, now actively working in different areas of biology. J. Watson was one of the initiators of the Human Genome Project and continues to work in the field of molecular biology, and F. Crick published an article on the nature of consciousness in early 2003.
J.D. Watson,
|
* Georgy Antonovich Gamov (1904–1968, emigrated to the USA in 1933) - one of the greatest scientists of the 20th century. He is the author of the theory of theta decay and the tunnel effect in quantum mechanics; liquid-droplet model of the atomic nucleus - the basis of theories of nuclear decay and thermonuclear reactions; theory of the internal structure of stars, which showed that the source solar energy are thermonuclear reactions; the “Big Bang” theory in the evolution of the Universe; theories of cosmic microwave background radiation in cosmology. His popular science books are well known, such as the series of books about Mr. Tompkins (Mr. Tompkins in Wonderland, Mr. Tompkins Inside, etc.), One, Two, Three... Infinity, A Planet Called Earth " and etc.
