По направленности своего действия все антибиотики можно разделить на следующие основные группы:
· противобактериальные антибиотики;
· противогрибковые антибиотики;
· противовирусные антибиотики;
· противоопухолевые антибиотики.
Некоторые авторы относят к антибиотикам не только те химические вещества, которые синтезируются микроорганизмами, но и неприродные соединения, синтезируемые химическими способами, полагая, что дело не столько в происхождении препарата, сколько в его антимикробной активности и полезности для человека.
Они включают в себя природные пенициллины, несколько поколений полусинтетических пенициллинов, несколько поколений цефалоспоринов, нетрадиционные бета-лактамы. Группа бета-лактамных антибиотиков активна против многих грамположительных и грамотрицательных аэробных и анаэробных бактерий.
XI. Talking points:
1. Modern biopharmaceuticals.
2. The variety of infections and the problem to cure them.
3. The definition of antibiotics and their classes.
4. Side effects and antibiotic resistance.
Unit 4
Genetic Engineering
Genetic engineering, genetic modification (GM) and gene splicing are terms for the process of manipulating genes, usually outside the organism’s normal reproductive process.
It involves the isolation, manipulation and reintroduction of DNA into cells or model organisms, usually to express a protein. The aim is to introduce new characteristics or attributes physiologically or physically, such as making a crop resistant to a herbicide, introducing a novel trait, or producing a new protein or enzyme. Examples can include the production of human insulin through the use of modified bacteria, the product ion of erythropoietin in Chinese Hamster Ovary cells, and the production of new types of experimental mice such as the Onco Mouse (cancer mouse) for research, through genetic redesign.
Since a protein is specified by a segment of DNA called a gene, future versions of that protein can be modified by changing the gene’s underlying DNA. One way to do this is to isolate the piece of DNA containing the gene, precisely cut the gene out, and then reintroduce (splice) the gene into a different DNA segment. Daniel Nathans and Hamilton Smith received the 1978 Nobel Prize in physiology or medicine for their isolation of restriction endonucleases, which are able to cut DNA at specific sites. Together with ligase, which can join fragments of DNA together, restriction enzymes formed the initial basis of recombinant DNA technology.
Applications
The first Genetically Engineered drug was human insulin approved by the USA’s FDA in 1982. Another early application of GE was to create human growth hormone as replacement for a drug that was previously extracted from human cadavers. In 1986 the FDA approved the first genetically engineered vaccine for humans, for hepatitis B. Since these early uses of the technology in medicine, the use of G E has expanded to supply many drugs and vaccines.
One of the best known applications of genetic engineering is that of the creation of genetically modified organisms (GMOs).
There are potentially momentous biotechnological applications of GM, for example 01 a I vaccines produced naturally in fruit, at very low cost.
A radical ambition of some groups is human enhancement via genetics, eventually by molecular engineering.
DNA sequencing is a technique which is used to identify each base in DNA Although the costs of DNA sequencing has dropped dramatically, the NIH estimates it costs at least $ 10 million to sequence 3 billion base pairs — the size of the whole human genome.
Genetic Engineering and Research
Although t here has been a tremendous revolution in the biological sciences in the past twenty years, there is still a great deal that remains to be discovered. The completion of the sequencing of the human genome, as well as the genomes of most agriculturally and scientifically important plants and animals, has increased the possibilities of genetic research immeasurably. Expedient and inexpensive access to comprehensive genetic data has become a reality with billions of sequenced nucleotides already online and annotated. Now that the rapid sequencing of arbitrarily large genomes has become a simple, if not trivial affair, a much greater challenge will be elucidating function of the extraordinarily complex web of interacting proteins, dubbed the proteome, that constitutes and powers all living things. Genetic engineering has become the gold standard in protein research, and major research progress has been made using a wide variety of techniques, including:
Loss оf function, such as in a knockout experiment, in which an organism is engineered to lack the activity of one or more genes. This allows the experimenter to analyze the defects caused by this mutation, and can be considerably use fill in unearthing the function of a gene. It is used especially frequently in developmental biology. A knockout experiment involves the creation and manipulation of a DNA construct in vitro, which, in a simple knockout, consist sola copy of the desired gene which has been slightly altered such as to cripple its function. The construct is then taken up by embryonic stem cells, where the engineered copy of the gene replaces the organism’s own gene. These stem cells are injected into blastocysts, which are implanted into surrogate mothers. Another method, useful in organisms such as Drosophila (fruit fly), is to induce mutations in a large population and then screen the progeny for t he desired mutation. A similar process can be used in both plants and prokaryotes.
Gain of function experiments, the logical counterpart of knockouts. These are sometimes performed in conjunction with knockout experiments to more finely establish the function of the desired gene. The process is much the same as that in knockout engineering, except that the construct is designed to increase the function of the gene, usually by providing extra copies of the gene or inducing synthesis of the protein more frequently.
«Tracking» experiments, which seek to gain information about the localization and interaction of the desired protein. One way to do this in to replace the wild-type gene with a «fusion» gene, which is a juxtaposition of the wild-type gene with a reporting element such as Green Fluorescent Protein (GFP) that will allow easy visualization of the products of the genetic modification. While this is a useful technique, the manipulation can destroy the function of the gene, creating secondary effects and possibly calling into question the results of the experiment. More sophisticated techniques are now in development that can track protein products without mitigating their function, such as the addition of small sequences which will serve as binding motifs to monoclonal antibodies.
Exercises
A.Comprehension
I. Answer these questions.
1. What are the aims and basic processes of genetic engineering?
2. How can a protein be specified and modified?
3. What applications of genet ic engineering do you know?
II. Name three kinds of experiments and characterize each of them.
III. Agree or disagree with these statements.
1. Genetic engineering involves the isolation, manipulation and reintroduction of DNA into cells or model organisms, usually to express a protein.
2. The first Genetically Engineered drug was penicillin.
3. A knockout experiment involves replacement of the wild-type gene with a “fusion” gene, which is a juxtaposition of t lie wild-type gene with a reporting element.
4. At function experiments the construct is designed to increase the function of the gene, usually by providing extra copies of the gene or inducing synthesis of the protein more frequently.
IV. Summarize the text, using vocabulary from Exercise 5.
B.Vocabulary
V. Give Russian equivalents of the following expressions:
| to splice genes | reintroduction | to glow |
| (gene) isolation | to cut out | vaccine |
| precisely | immeasurably | luciferase |
| hormone | human enhancement | novel trait |
| cadaver | unearthing | DNA sequencing |
| to elucidate | expedient | annotated |
| to cripple | Progeny | to track |
| sophisticated | to mitigate |
VI. Find synonyms of these expressions among the words and word combinations in the previous exercise.
1) separation; seclusion; segregation;
2) greatly; enormously; considerably; hugely; immensely;
3) highly developed; complicated; difficult;
4) to make clear; clarify; explain; illuminate; reveal;
5) corpse; dead body; remains;
6) exactly, accurately; specifically; correctly;
7) detection; finding; sighting;
8) to blaze; shine; flush; flame;
9) original; new; fresh; different; innovative; unusual; unique;
10) offspring; children; descendants.
VII. Translate the given words and expressions into English:
1)соединять гены; 2)изоляция (генов); 3)повторное внедрение, введение; 4)новый признак; 5)точно, строго; 6)отделять, выводить; 7)гормон; 8)труп; 9)вакцина; 10)увеличение численности населения; 11)секвенирование ДНК; 12)неизмеримо; 13)целесообразный; 14)обоснованный; 15)разъяснять; 16)обнаружение, выявление; 17)нарушать; 18)потомство; 19)прослеживать, наблюдать; 20)усовершенствованный, сложный; 21)уменьшать, сдерживать.
Find the sentences in the text, where these words and expressions are used. Translate them into Russian.
С. Reading, Writing and Discussion
VIII. Read the text carefully, without a dictionary. While reading, pay special attention to the words that you don’t know: look cam fully at the context and see if you can get the idea of what they mean. After reading speak on: 1) fundamental weaknesses of the concept; 2) health hazards; 3) environmental hazards. Write a summary of the text. Express your own opinion on the problems.
What are the Dangers?
Imprecise Technology. A genetic engineer moves genes from one organism to another. A gene can be cut precisely from the DNA of an organism, but the insertion into the DNA of the target organism is basically random. As a consequence, there is a risk that it may disrupt the functioning of other genes essential to the life of that organism.
Side Effects. Genetic engineering is like performing heart surgery with a shovel. Scientists do not yet understand living systems completely enough to perform DNA surgery without creating mutations which could be harmful to the environment and our health. They are experimenting with very delicate, yet powerful forces of nature, without fill knowledge of the repercussions.
Widespread Crop Failure. Genetic engineers intend to profit by patenting genetically engineered seeds. This means that, when a farmer plants genetically engineered seeds, all the seeds have identical genetic structure. As a result, if a fungus, a virus, or a pest develops which can attack this particular crop, there could be widespread crop failure.
Threatens Our Entire Food Supply. Insects, birds, and wind can carry genetically altered seeds into neighboring fields and beyond. Pollen from transgenic plants can cross-pollinate with genetically natural crops and wild relatives. All crops, organic and non-organic, are vulnerable to contamination from cross-pollinatation.
No Long-Term Safety Testing. Genetic engineering uses material from organisms that have never been part of the human food supply to change the fundamental nature of the food we eat. Without long-term testing no one knows if these foods are safe.
Toxins. Genetic engineering can cause unexpected mutations in ml organ ism, which can create new and higher levels of toxins in foods.
Allergic Reactions. Genetic engineering can also produce unforeseen and unknown allergens in foods.
Decreased Nutritional Value. Transgenic foods may mislead consumers with counterfeit freshness. A luscious-looking, bright red genetically engineered tomato could be several weeks old and of little nutritional worth.
Antibiotic Resistant Bacteria. Genetic engineers use antibiotic-resistant genes to mark genetically engineered cells. This means that genetically engineered crops contain genes which confer resistance to antibiotics. These genes may be picked up by bacteria which may infect us.
Problems Cannot Be Traced. Without labels, our public health agencies are powerless to trace problems of any kind back to their source. The potential for tragedy is staggering.
Side Effects can Kill. 37 people died, 1500 were partially paralyzed, and 5000 more were temporarily disabled by a syndrome that was finally linked to tryptophan made by genetically-engineered bacteria.
Increased use of Herbicides. Scientists estimate that plants genetically engineered to be herbicide-resistant will greatly increase the amount of herbicide use. Farmers, knowing that their crops can tolerate the herbicides, will use them more liberally.
More Pesticides. GE crops often manufacture their own pesticides and may be classified as pesticides by the EPA This strategy will put more pesticides into our food and fields than ever before.
Ecology may be damaged. The influence of a genetically engineered organism on the food chain may damage the local ecology. The new organism may compete successfully with wild relatives, causing unforeseen changes in the environment.
Gene Pollution Cannot Be Cleaned Up. Once genetically engineered organisms, bacteria and viruses are released into the environment it is impossible to contain or recall them. Unlike chemical or nuclear contamination, negative effects are ii reversible.
DNA is actually not well understood. The workings of a single cell are so complex, no one knows the whole of it. Yet the biotech companies have already planted millions of acres with genetically engineered crops, and they intend to engineer every crop in the world.
The concerns above arise from an appreciation of the fundamental role DNA plays in life, the gaps in our understanding of it, and the vast scale of application of the little we do know. Even the scientists in the Food and Drug administration have expressed concerns.
random — случайный, наугад; surgery—хирургия; repercussions — последствия; pollen — опылять; counterfeit — ложный; hazard — риск
IX. Retell the text in English.
Генная инженерия — совокупность приёмов, методов и технологий получения рекомбинантных РМК и ДНК, выделения генов из организма (клеток), осуществления манипуляций с генами и введения их в другие организмы. Генная инженерия служит для получения желаемых качеств изменяемого организма.
Генная инженерии не является наукой к широком смысле, но является инструментом биотехнологии, используя исследования таких биологических наук, как молекулярная биология, цитология, генетика, микробиология. Самым ярким событием, привлекшим наибольшее внимание и очень важным по споим последствиям, была серия открытий, результатом которых явилось создание методов управления наследственностью живых организмов, причём управлении путём проникновения в «святая святых» живой клетки в её генетический аппарат.
Учёные, биохимики и молекулярные биологи научились модифицировать гены или создавать совершенно новые, комбинируя гены различных организмов. Они научились также синтезировать гены, причём точно по заданным схемам. Они научились вводить такие искусственные гены в живые организмы и заставили их там работать. Это было начало генетической инженерии. Задумаемся над следующим обстоятельством.
Основа микробиологической, биосинтетической промышленности — бактериальная клетка. Необходимые для промышленного производства клетки подбираются по определённым признакам, самый главный из которых —способность производить, синтезировать, при этом в максимально возможных количествах, определённое соединение — аминокислоту или антибиотик, стероидный гормон или органическую кислоту.
Иногда надо иметь микроорганизм, способный, например, использовать в качестве «пищи» нефть или сточные воды и перерабатывать их в биомассу или даже вполне пригодный для кормовых добавок белок. Иногда нужны организмы, способные развиваться при повышенных температурах или в присутствии веществ, безусловно смертельных для других видов микроорганизмов. Задача получения таких промышленных штампов очень важна, для их видоизменения и отбора разработаны многочисленные приёмы активного воздействия на клетку—от обработки сильнодействующими ядами до радиоактивного облучения.
Цель этих приёмов одна — добитых изменения наследственного, генетического аппарата клетки. Их результат — получение многочисленных микробов-мутантов, из сотен и тысяч которых ученые потом стараются отобрать наиболее подходящие для той или иной цели. Создание приёмов химического или радиационного мутагенеза было выдающимся достижением биологии.
Но их возможности ограничиваются природой самих микроорганизмов. Они не способны синтезировать ряд ценных веществ, которые накапливаются в растениях, прежде всего в лекарственных и эфирномасличных. Не могут синтезировать вещества, очень важные для жизнедеятельности животных и человека, ряд ферментов, пептидные гормоны, иммунные белки, интерфероны, да и многие более просто устроенные соединения, которые синтезируются в организмах животных и человека. Разумеется, возможности микроорганизмов далеко не исчерпаны. Из всего изобилия микроорганизмов использована наукой, и особенно промышленностью, лишь ничтожная доля.
Для целей селекции микроорганизмов большой интерес представляют, например, бактерии анаэробы, способные жить в отсутствие кислорода, фототроты, использующие энергию света подобно растениям, хемоавтотрофы, термофильные бактерии, способные жить при температуре, как оказалось недавно, около 250 °С (олово плавиться при температуре 232 °С), и др.
И всё же ограниченность «природного материала» очевидна. Обойти ограничения пытались и пытаются с помощью культур клеток и тканей растений. Это очень важный и перспективный путь. За последние несколько десятилетий учёные создали методы, благодаря которым отдельные клетки тканей растения или животного можно заставить расти и размножаться отдельно от организма, как клетки бактерий.
Это было важное достижение — полученные культуры клеток используют для экспериментов и для промышленного получения некоторых веществ, которые с помощью бактериальных культур получить невозможно. Но здесь тоже есть свои трудности, например неспособность животных клеток в культуре делиться бесконечное число раз, как это происходит с бактериями.
Кроме того, получить и выращивать культуры клеток труднее, чем бактериальные культуры. Учёные стремились научиться изменять гены, вводить нужные гены в живой организм, так сказать, «редактировать» книгу природы.
PHK-RNA
X. Read and translate the text without a dictionary.
DNA is the blueprint for the individuality of an organism. The organism relies upon the information stored in its DNA for the management of every biochemical process. The life, growth and unique features of the organism depend on its DNA. The segments of DNA which have been associated with specific features or functions of an organism are called genes.
Molecular biologists have discovered many enzymes which change the structure of DNA in living organisms. Some of these enzymes can cut and join strands of DNA. Using such enzymes, scientists learned to cut specific genes from DNA and to build customized DNA using these genes. They also learned about vectors, strands of DNA such as viruses, which can infect a cell and insert themselves into its DNA
With this knowledge, scientist stalled to build vectors which incorporated genes of their choosing and used the new vectors to insert these genes into the DNA of living organisms. Genetic engineers believe they can improve the foods we eat by doing this. For example, tomatoes are sensitive to frost. This shortens their growing season. Fish, on the other hand, survive in very cold water. Scientists identified a particular gene which enables a flounder to resist cold and used the technology of genetic engineering to insert this «anti-freeze» gene into a tomato. This makes it possible to extend the growing season of the tomato.
XI. Talking points:
1. Aims of genetic engineering process and its application.
2. Genetic engineering and research.
3. Danges of genetic engineering application.
Unit 5
Genetically Modified Organism
A genetically modified organism (GMO) is an organism whose genetic material has been altered using techniques in genetics generally known as recombinant DNA technology. Recombinant DNA technology is the ability to combine DNA molecules from different sources into the one molecule in a test tube. Thus, the abilities or the phenotype of the organism, or the proteins it produces, can be altered through the modification of its genes.
The term generally does not cover organisms whose genetic makeup has been altered by conventional cross breeding or by «mutagenesis» breeding, as these methods predate the discovery of the recombinant DNA techniques. Technically speaking, however, such techniques are, by definition, genetic modification.
Examples of GMOs are diverse, and include transgenic experimental animals such as mice, several fish species, transgenic plants, or various microscopic organisms altered for the purposes of genetic research or for the production of pharmaceuticals. One of the latest examples of this technology is the development of transgenic chickens that will deposit pharmaceutical products in the egg white, using the ovalbumin promoter linked, in this case, to a human sequence antibody cassette (where the light and heavy chain variable regions are introduced) The term «genetically modified organism» does not necessarily imply, but does include, transgenic substitution of genes from another species, and research is actively being conducted in this field. For example, genes for fluorescent proteins can be со-expressed with complex proteins in cultured cells to facilitate study by biologists, and modified organisms are used in researching the mechanisms of cancer and other diseases.
