WATSON AND CRICK DESCRIВE STRUCTURE OF DNA

What is DNA? DNA stands for deoxyribonucleic acid. This is а substance that is present in every living cell. However, each living cell thing has а different kind of DNA The kind of DNA you have in your cells gives you all the features you inherit from your parents. Iн the late nineteenth century, а German biochemist found that the nucleic acids, long-chain polymers of nucleotides, were made up of sugar, phosphoric acid, аnd several nitrogen-containing bases. Later it was found that the sugar in nucleic acid can bе ribose or deoxyri¬bose, giving two forms. RNA аnd DNA. In 1943, American Oswald А very proved that DNA carries genetic information. Не even suggested DNA might actually bе the gene. In 1948, Linus Pauling discovered that many proteins take the shape of an alpha helix, spiraled like а spring coil. In 1950, biochemist Erwin Chargaff found that the arrangement of nitrogen bases in DNA varied widely, but the amount of certain bases always occured in а one-to-one ratio. These discoveries were ап important foundation for- die later description of DNA. Iт the early 1950s, the race to discover DNA was on. At Cani- bridge: University, graduate student Francis Crick апd research fellow James Watson (Ь. 1928) had become interested, impressed especially bу Pauling's work. Meaпwhile at Кing's College in London, Maurice Wilkins (Ь. 1916) апd Rosalind Franklin 'ere also studying; DNA. The Cambridge team's approach was to make physical models to nar¬row down the possibilities апd eventually create an accurate picture of the molecule. The King's team took ап experimental approach, look¬ing particularly at x-ray diffraction images of DNA. In 1951, Watson attended а lecture bу Franklin on her work to date. She had found that DNA сап exist in two forms, depending оп the relative humidity ш the surrounding air. This had helped her de¬duce that the phosphate раrt of the outside was on the outside. Wat¬son returned to Cambridge with а rather muddy recollection of the facts Franklin had presented, though clearly critical of her lecture style and personal арреаrаnсе. Based оп this information, Watson and Crick made а failed model. It caused the head of their unit to tel1 them to stop DNA research. But the subject just kept coming up. Franklin, working mostly alone, found that her x-ray diffractions showed that the "wet" form of DNA (in the higher humidity) had all the characteristics of .а helix. She suspected that all DNA was helical but did not want to аnоnсе this finding until she had sufficient evi¬dence on the other form as well. Wilkins was frustrated. In January, 1953, he showed Franklin's results to Watson, apparently without her knowledge or coпsen1. C1•ick later admitted, "I'm afraid we always used to adopt - let's say, а patronizing attitude towards her." Watson and Crick took а crucial conceptual step, suggesting the molecule was mаdе of two chains of nucleotides, each in а helix as Frank1in had found, bot оnе going up and the other going down. Crick had just learned of Chargaff’s findings аbоut base pairs in the sum¬mer of 1952. Не added that to the mode1, so that matching base pairs interlocked in the middle of the double helix to keep the distance be¬tween the chains constant. Тhе structure so perfectly fit the experimental data that it was almost immediately accepted. DNA's discovery has been сallеd the most important biological work of the la.st 1 00 years, and the fie1d it opened may bе the scientific frontier for the next 100. Ву 1962, when Watson, Crick, аnd Wilkins won the, Nobel Prize for physiol¬ogy/medicine, Franklin has died. The Nobel Prize only goes to living recipients, and сап опlу bе shared among three winners. Was she alive, wou1d she have bееn included in the prize?

LIFE. ITS CНARACTERISTICS (магистры 1 курс)

The quantity of life an organism possess cannot bе measured, alt¬hough the average person distinguishes between the living and non living state in familiar organisms, either plants or animals. Life, there¬fore, cannot easily bе defined but is described in teams of а series of special attributes, as follows: Organization. Living matter has а characteristic type of organisation occurring in several levels. Living material is called proto¬plasm. This is not а definite chemical compound but а complex mix¬ture varying in different organisms and different parts of the same or¬ganism. Protoplasm is aggregated in structural units called cells which iп larger organisms are combined to form organs. And the whole ani¬mal plant behaves as а unit, an organism. A Metabolism. Metabolism is the sнm total to all chemical processes going on in living matter. These processes, in part, occur in а living matter: and are, therefore, characteristic. Constructive (synthetic) pro¬cesses constitute anabolism; destructive metabolism is catabolism. Growth. An excess of synthetic over destructive processes in me¬tabolism results in an increase in size. This process of growth (does not consist of the addition of material оn the surface нt of an increase in all pai1s. Reproduction. When а cell has growth to а characteristic size, it divides, forming two. In а one-celled organism this is reproduction. In а multicellular organism it is not only reproduction of cells but growth of the, whole organism. Reproduction in multicellular organism may take place asexually when only one parent is involved, or sexually when two parents are involved. In either case, offspring resempling the parent or parents is produced. Adaptation. The innate fitness of an organism for the environnment, in which it lives and thrives is called adaptation. Adaptation develops throщ;h various evolutionary mechanisms, and, it becomes permanent though inheritance. 1. Cuestions for discussion. 1) Сап we easily define, life? 2) What terms must bе used in description of life? 3) How is living material called? 4) What is protoplasm'? 5) What is protoplasm aggregated in? 6) What is the cell? 7) Why are cells iп largero rganism's combine? 8) What helps аn animal or а рlant to behave as а unit? 9) What is metabolism? 10) What is соnstructive (destructive) metabolism called? ] 11) How саn you definite growth of living organisms? 12) When is the cell ready for reproduction? 13) How many cells сап an organism have? 14) In what case may reproduction take place asexually (sexually)? 15) How сап your account tor irritabllity? 16) What does adaptation mean? П. Ask questions to each sentence given below. Тhе study of the world of life is as old as man himself. Our an-cestors were aware of' the differences between а bat and а bird and long before they had а11 inkling that there were similarities between the issues of а mushroom апd а ma11. The awarerness that aII organisms have certain common principles dates back to the cell 1heory. This theory, enunciated bу Schleiden ап Schwan in 1833, stated tl1at all living systems are composed of cells and of cell products. The cell is the common denominator of all the immense variety of living forшs. One must not forget that all cells have specialized юles over tl1e entire range of diversity in biological form and function. Пl. Translate into Englislh. Познание сущности жизни - одна из основных задач общей биологии главными закономерностями, характеризующими жизнь, являются: структурная организация, обмен веществ и энергии, репродукция, рост, раздражимость, адаптация. IV: Маkе а presentation to the text.

Lister, the founder of antiseptic surgery (2 курс)

Lister, the founder of antiseptic surgery Sir Joseph Lister (1827-1912) made а notable contribution in the field of surgery in 1867,while Lister was а professor of surgery in the University of Glasgow, he began to experiment with the use of carbolic acid in the treatment of wounds. Prior to this time there was always great danger of gangrene after operation. In the beginning he applied concentrated caroof1c acid to the wound. Gangrene did not develop, but this method was exceedingly painful and often resulted in large, ugly scars. What did he do to avoid, these results? Не saturated silk gauze with the acid applied the gauze to the wound а method that proved far more successful. Lister next directed attention to materials that used, when he stitched the wounds. Later he began to use catgut which he treated with sulfur and chromium as the most reliable material. Did he do anything else? Yes, he did. In 1869 Lister turned his at¬tention to the destruction of harmful bacteria in the air: Before he per¬formed an operation he sprayed the atmosphere with а week solution of carbolic acid. Then he began to sterilize everything he used in the operation itself. Нis next step, therefore, was to develop а technique for пsing antiseptic on the hands, dressings, sponges, bandages, und surgical instruments. And now modern medicine still uses Lister' s antiseptic method in surgery.

V. Translate the following sentences into English using the active words: 1. Мы вышли из лесу и увидели большое пшеничное поле. 2. В какой области биологии он работает? 3. Ветер отломил большую ветвь у яблони, которая растет в углу сада. 4. В Новосибирске есть филиал Академии Наук. 5. В этом месте железная дорога разветвляется в трех направлениях. 6. Кто первый отметил кар- боловую кислоту при обработке ран? 7. Новое средство нашло свое применение для лечения сердечных болезней. 8. Этот врач руководил всем хирургическим отделением больницы. 9. Это растение растет только, если оно получает прямой солнечный свет. 10. Мы пошли в направлении высокого здания, которое показалось вдали. 11. В первое утро, когда мы приехали на дачу, мы рано встали, оделись, быстро позавтракали и пошли в лес. 12. Листер обрабатывал карболовой кислотой не только раны, но и пропитывал ею весь перевязочный материал. 13. В результате сложной операции и правильного лечения ребенок выздоровел. 14. Вы не знаете, каковы результаты его беседы с директором? 15. Выветривание (weathering) приводит к разрушению горных пород.