Follow-Up

Clone

also spelled CLON, population of genetically identical cells or organisms that are derived originally from a single original cell or organism by asexual methods. Cloning is fundamental to most living things, since the body cells of plants and animals are clones ultimately derived from the mitosis of a single fertilized egg. More narrowly, a clone can be defined as an individual organism that was grown from a single body cell of its parent and that is genetically identical to it.

Plants that are able to propagate by asexual means produce genetically identical plants that are clones. Cloning has been commonplace in horticulture since ancient times; many varieties of plants are cloned simply by obtaining cuttings of their leaves, stems, or roots and replanting them. A vast array of fruit and nut tree varieties and innumerable ornamental plants represent clones.

The body cells of adult animals and humans can be routinely cloned in the laboratory. Adults cells of various tissues, such as muscle cells, that are removed from the donor animal and maintained on a culture medium while receiving nutrients manage not only to survive but to go on dividing, producing colonies of identical descendants. By the 1950s scientists were able to clone frogs, producing identical individuals that carry the genetic characteristics of only a single parent. The technique used in the cloning of frogs consists of transplanting frog DNA, contained in the nucleus of a body cell, into an egg cell whose own genetic material has been removed. The fused cells then begin to grow and divide, just like a normal fertilized egg, to form an embryo.

Mice were first successfully cloned in the 1980s, using a procedure in which the nucleus from a body cell of a mouse embryo is removed from the uterus of a pregnant mouse and transplanted into a recently fertilized egg (from another mouse) whose genetic contents have been evacuated. The cell is cultured artificially until it divides and becomes an embryo. The embryo, which is composed entirely of cells derived from the single implanted nucleus, is artificially implanted into the uterus of another mouse that brings it to term.

Cloning a new animal from the cells of an adult (as opposed to those of an embryo) is considerably more difficult, however. The first success in cloning an adult mammal was achieved by a team of British researchers led by Ian Wilmut at the Roslin Institute in Edinburgh, Scot., in 1996. After having already produced clones from sheep embryos, they were able to produce a lamb using DNA from an adult sheep. In their procedure, the nucleus of a cell from the mammary gland of an adult sheep was implanted in another sheep's unfertilized egg whose nucleus had been removed.

The practical applications of cloning are economically promising but philosophically unsettling. Animal breeders would welcome the chance to clone top-quality livestock. Genetically engineered animals could be cloned in large numbers to increase the production of drugs or human proteins that are useful in fighting disease. Clones are also highly useful in biological research because of their genetic uniformity.

The cloning of human beings is a subject fraught with ethical and moral controversy. If cloning can ensure the infinite replication of specific genetic traits, a judgment would need to be made as to which traits are desirable and therefore worthy of perpetuation. The persons empowered to exercise such judgment would be in a position to change the course of human development.

Biotechnology--Blessing or Curse?

Recent advances in plant biotechnology have produced a stunning array of seemingly hardier plants, growing in more climates and producing more and better fruits. Some view this second generation of modified crops as a bountiful blessing, but others see it as a disguised curse. Some fear hidden dangers to those who consume the recombinant crops, whereas others worry about damage to the environment, including potential compromises of biodiversity. Similar concerns must have been raised generations ago when the first hybrid grains and chemical fertilizers were introduced. In recent years the furor over genetically modified foods in the marketplace has been particularly keen in Great Britain and other nations of the European Union, with ripples in the U.S. and other parts of Europe.

Public acceptance of genetically modified foodstuffs might be expected to be sluggish as long as the benefits of genetic engineering were enjoyed mainly by the producers rather than the consumers. Food prices in the developed world were already low enough that consumers had no real reason to care whether a particular crop was easier or cheaper to grow. Now that more of the benefits of genetic modification--improved taste, longer shelf life, and enhanced health benefits--are oriented directly toward the consumer, however, the public may prove more receptive.

I. Answer the questions:

1. What is genetic engineering? Which substances have been produced in this manner?

2. What are the techniques of genetic engineering and which effects do they bring?

3. Which year can be regarded as the birth-year of biotechnology?

4. What does the term recombinant DNA literally mean?

5. Which possibilities does this technique have?

6. Why is biotechnology a matter of public concerns and debates?

II. Read the part ‘Cloning’ once again and say whether these statements are true or false.

1. A clone is an individual organism that is derived originally from a single body cell of its parent and is genetically identical to it.

2. A vast array of plants grown from the cuttings of their leaves, stems, or roots can’t be called clones.

3. Frogs were cloned using a procedure in which the nucleus from a body cell of its embryo was transplanted into a recently fertilized egg from another frog.

4. While cloning mice, a body cell was transplanted into an egg whose genetic content had been evacuated.

5. The first cloned mammal was a sheep.

6. The practical applications of cloning are economically unsettling.

III. Which biotechnology applications among mentioned above do you consider beneficial? Which of them are detrimental?

• Detection of inherited diseases (the use of genetic tests to detect inherited diseases)
• Human genes in bacteria (the introduction of human genes in bacteria to produce medicines or vaccines)
• Development of GM bacteria (the genetic modification of crops to make them more resistant to insects)
• Food production (genetically modified fruit and transgenic food)
• Animal and human being cloning
• Recreation of organs using versatile stem cells

9. Read the examples of scientific achievements in biotechnology and render them in English. Comment on them.

1. Австралийские учёные намерены клонировать вымершего более 60 лет назад тасманского тигра. Надежду на успех операции учёным придала находка целой молекулы ДНК в заспиртованном в 1886 году теле тигрёнка, заявил руководитель проекта в Сиднее. Эти хищные животные были беспощадно истреблены, поскольку нападали на овчарни. Последний тасманский тигр умер в 1936 году в зоопарке города Хобарт.
2. В конце февраля неудачей закончилась встреча представителей правительств 170 стран в Колумбийском городе Картахена, посвящённая обсуждению так называемого «Протокола о биологической безопасности». Главным камнем преткновения, как и на предыдущих совещаниях, оказались вопросы контроля над межгосударственным перемещением генетически измененных растений и животных.
3. Южнокорейским ученым удалось клонировать корову. Литовские ученые накопили достаточно знаний, чтобы клонировать человека. Врачи Чикагского университета планируют провести первые испытания искусственной печени, использующей вместо донорской ткани животных клонированные клетки человека.
4. Клонированная овечка Долли казалась внешне молодой, а её развитие – совершенно нормальным, однако, как показали исследования её хромосом, организм овцы уже при рождении был биологически преждевременно состарившимся. Исследователи Рослинского института в Эдинбурге, которых насторожили аномалии в хромосомах Долли, обнаружили, что организм овцы был по меньшей мере на 6 лет старше своего реального возраста.
5. По сообщению независимого информационного агентства, уже в ближайшие несколько месяцев создатели овечки Долли подадут в правительство заявление с просьбой разрешить эксперименты по клонированию людей. Основным препятствием на пути исследований являются моральные соображения. Конечным итогом работ создателей Долли должно стать появление средств лечения таких опасных заболеваний, как болезни Паркинсона и Альцгеймера.

10. Listen to the results of the survey in Europe. Fill in the gaps with the information omitted. Is the issue of biotechnology a matter of public concern and debate in Russia? Why? Would you like to be better informed about the recent advances in this sphere?

________ per cent of people think about animal and human being cloning when asked about their associations with biotechnology. Biotechnology appears to be a matter of great public concern for _________ of people who frequently discuss this subject.

This subject ____________ a lot of media attention, which makes people to be in the know of the current events in the sphere.

In general, people have rather negative feelings towards cloning. Assessing the statements on a scale of 1 to 5, Europeans gave the strongest support - ____ to the statement ____________________________________________________________________ A low average, ________, close to ‘do not agree’ scored the statement ____________________________________________________________________

The results of the survey showed that women are more __________________ than men when it comes to the idea of identical reproduction. One more conclusion is that the attitude to biotechnology applications depends on the socio-professional category and age of people.

11. Read the opinions of different people on the problem of cloning. Find the following words and phrases while reading:

генетические и врождённые дефекты; шумиха; молчаливо соглашаться; независимая проверка/экспертиза; прокладывать дорожку, ведущую к тому, о чём будем сожалеть; ни малейшей разумной мысли; уничтожить болезнь; большое пространство для злоупотреблений; скользкий путь.

Should Human Cloning Be Banned?

Once collective human knowledge crosses a barrier, it is difficult to reverse it through social, political or religious constraints. How could an effective ban on cloning be defined and why should we do it? I wonder if many people who are vocal against cloning really understand the process, the results and potential benefits in treating genetic and congenital defects. Also wonder why we didn’t have this kind of a reaction against test tube babies, which is also an unnatural process.

Дата добавления: 2014-11-16