Table 10.1. The Major Molecules and Cells of the Immune Response
| Molecules | |
| _________________ | Large organic molecules, normally proteins, polysaccharides, or glycoproteins, that can trigger an immune response, typically located on the surface of cells. |
| Antibodies | _______________________________________________________ |
| Major histocompatibility complex (MHC) | A set of proteins found on the surface of cells that “label” the cell as belonging to a unique individual organism. |
| Effector molecules | A diverse group of molecules, including histamine and the cell-destroying proteins of killer cells and complement (soluble proteins found in blood). |
| _________________ | Hormonelike molecules produced by cells of the immune system that regulate the immune response. |
| Cells | |
| Macrophages | _______________________________________________________ |
| ____________________ | Lymphocytes that produce antibodies; when stimulated, certain of their daughter cells (plasma cells) secrete large quantities of antibodies into the bloodstream. |
| ____________________ | A set of lymphocytes that regulate the immune response or kill certain types of cells. |
| Cytotoxic T cells | Destroy specific targeted cells, normally either foreign eukaryotic cells, infected body cells, or cancerous body cells. |
| Helper T cells | Stimulate immune responses by both B cells and killer T cells. |
| Suppressor T cells | Inhibit immune responses by other lymphocytes. |
| ____________________ | A subset of the offspring of B and T cells that are long-lived and provide future immunity against a second invasion by the same antigen. |
Reading
I. Read and translate the following text.
Cellular Communication during the Immune Response
The immune system is a strange “system”. Unlike the nervous system, for example, it is not composed of physically attached structures. Instead, as befits its mission of patrolling the entire body for microbial invaders, the immune system consists of an army of separate cells. Nevertheless, the army is highly coordinated. This coordination requires complex communications involving antigens, antibodies, hormones, receptors, and cells. For example, when a virus invades the body (step 1), it sets off a cascade of events that can be loosely divided into three components.
I. Activation of Helper T Cells.
One component of the immune response begins when macrophages ingest the virus (step 2) and digest it. Antigens that have been “chewed off” the virus become attached to certain proteins of the macrophage’s major histocompatibility complex (MHC) and are displayed, or presented, on the surface of the macrophage. These antigen-MHC complexes are recognized by virgin helper T cells (step 3). Next, receptors on helper T cells release a hormone called interleukin-2 (step 4). This hormone stimulates cell division and differentiation (step 5) in both the releasing cell and in any other T cells that have bound to an antigen-MHC complex. Some of the resulting daughter helper T cells become memory cells that provide future immunity (step 6); other daughter cells become mature T cells that assist in activating – that is, stimulating the immune response of – cytotoxic T cells and B cells (step 7).
II. Activation of Cytotoxic T Cells: Cell-Mediated Immunity.
Meanwhile, other copies of the virus are infecting ordinary body cells, such as those lining the respiratory tract (step 8). Infected body cells display viral antigens on their surfaces, bound to another set of MHC molecules. Virgin cytotoxic T cells bind to the antigen-MHC complex on the body cells (step 9) and are simultaneously activated by interleukin-2 released by the activated helper T cells. This combination of binding and stimulation causes the cytotoxic T cells to multiply and become activated (step 10). When activated cytotoxic T cells then encounter infected cells presenting the antigen-MHC complex, the T cells release toxic proteins that kill the infected cell by lysis (step 11).
III. Activation of B Cells: Humoral Immunity.
Some B cells bear antibodies on their surfaces that bind antigens on the surface of free viruses that have not yet invaded a body cell (step 12). This antigen-antibody binding stimulates some B cell division and maturation, but full activation of B cells requires a boost from helper T cells. This boost is provided when B cells that have bound antigen ingest that antigen (by receptor-mediated endocytosis), attach the antigen to MHC molecules, and present the antigen-MHC complex on their surfaces. The antigen-MHC complex is recognized by activated helper T cells (step 13), which then release several types of interleukin hormones that stimulate the division and differentiation of antigen-binding B cells (step 14). Some of the progeny become memory cells (step 15); other become plasma cells that secrete antibodies into the bloodstream (step 16).
As you can see, helper T cells are essential in turning on both phases of the immune response. A loss of helper T cells, such as that caused by the virus that causes AIDS, virtually eliminates the immune response to many diseases.
II. This interlocking communication network is quite complex. Try to summarize its essentials in five generalizations.
Language focus 1
Will and Shall
1 In offers, promises, orders and requests, will (or ‘ll) generally expresses willingness or wishes (this is connected with an older use of will to mean ‘wish’ or ‘want’).
This box looks heavy. I’ll help you with it. (offer)
I won’t tell anyone what happened. I promise. (promise)
Will you open the window, please? (request, wish)
Shall expresses obligation (like a more direct form of should) and is used mostly in questions.
What shall we do now?
Compare Shall I …? and Will you… ?:
Shall I shut the door? (= Do you want me to shut it?)
Will you shut the door? (= I want you to shut it.)
2 We can use will to talk about typical behaviour.
She’ll sit talking to herself for hours.
Under these conditions the process will be irreversible.
The door won’t open.
Sulphuric acid will dissolve most metals.
Stressed will can be used to criticize people’s typical behaviour.
She WILL always argue.
Well, if you WILL keep telling people what you think of them…
I. Complete the sentences with I’ll + a suitable verb.
1. ‘Are you coming with us?’ ‘No, thank you. I think I’ll ………. here’.
2. ‘Would you like tea or coffee?’ ‘………. coffee, please.’
3. ‘Do you want me to finish the experiment?’ ‘No, it’s all right. ………. it.’
4. ‘We haven’t got any samples.’ ‘Oh, haven’t we? ………. and get some.’
5. Thank you for lending me your camera. ………. it back to you on Tuesday.
II. What do you say in these situations? Write sentences with Shall I…? or Shall we…?
1. You and your classmates want to do something this evening but you don’t know what. You ask your friends:…………………………………………………….......?
2. It’s your best friend’s birthday. You want to give him/her a present but you don’t know what. Your ask another friend for advice: What…………………………………….…………………………………………?
3. You and a friend are going out. You haven’t decided whether to go by car or to walk. You ask him/her:……………..……………………………………………..?
4. Your boss wants you to phone later. You don’t know what time to phone. You ask him/her:………………………………………………………………………..?
III. Use modal verbs shall and will in short dialogues of your own to express your promise, suggestion, instruction, to say about decisions that have already been made, to inform about some properties and someone’s typical behaviour.
Words, Words, Words
I. Choose the appropriate modal verb while reading the essay.
Flu – The Unbeatable Bug
Every winter, a wave of influenza, or flu, sweeps across the world. Thousands of the elderly, the newborn, and those already suffering from illness succumb, while hundreds of millions more suffer the respiratory distress, fever, and muscle aches of milder cases. Occasionally, devastating flu varieties appear. In the great flu pandemic of 1918, the worldwide toll was 20 million dead in one winter. In 1968, the Hong Kong flu infected 50 million Americans, causing 70,000 deaths in 6 weeks.
Flu is caused by several viruses that invade the cells of the respiratory tract, turning each cell into a factory for manufacturing new viruses. The outer surface of a flu virus is studded with proteins, some of which are recognized by the immune system as antigens. This recognition ensures that most people survive the flu because their immune systems inactivate the viruses or kill off virus-infected body cells before the viruses finish reproducing. This is the same mechanism by which other viruses, such as those that cause mumps or measles, are conquered. So why (must/can’t) we become immune to the flu, as we (can/may) to measles?
The answer lies in a flu virus’s amazing ability to change. Flu virus genes are made up of RNA, which lacks the proofreading mechanisms that reduce mutations in genes made of DNA. Therefore, flu RNA genes mutate rapidly: on average, 10 mutations will appear in every million newly synthesized viruses. Most single mutations do not change the properties of the viral antigens very much. Four or five mutations in the same virus, however, (may/must) alter the surface antigens enough that the immune system does not fully recognize the virus as the same old flu that was beaten off last year. Some of the memory cells do not recognize it at all, and the immune response produced by the rest of the memory cells does not work as well as it (could/should). The virus although slowed down somewhat, gets a foothold in the body and multiplies until a new set of immune cells recognizes the mutated antigens and starts up a new immune response. So you get the flu again this year.
Far more serious are the dramatically new flu viruses that occasionally appear, as in the epidemic of 1918, the Asian flu of 1957, and the Hong Kong flu of 1968. In these viruses, entirely new antigens seem to appear suddenly. The novel antigens are not just slight variations of the old set, but they have distinctive structures that the human immune system has never before encountered. Where do the genes that encode these new antigens come from? Believe it or not, they come from viruses that infect birds and pigs. The intestinal tracts of birds, especially ducks, (can/may) host viruses strikingly similar to human flu viruses, though infected birds suffer from no noticeable disease. The human flu viruses do not infect birds. But both human and bird viruses (can/might) infect pigs, so both viruses (must/can) in some cases simultaneously infect the same pig cell. Once in a great while (perhaps only three times during the twentieth century), new viruses that spring from a double-infected pig cell end up with a mixture of genes from human and bird viruses. Some of these hybrid viruses combine the worst genes (at least from our perspective) of each: from the human virus, the deadly new viruses pick up the genes needed to subvert human cellular metabolism to produce new viruses; from the bird virus, they pick up genes for new surface antigens. The hybrid viruses (can/could) move easily from pigs to humans, because pigs live near humans and, like us, pigs cough when they have the flu.
Have you ever wondered why flu strains are called “Asian” or “Hong Kong”? The reason is that Southeast Asia is usually the place where new strains crop up. Many farmers in Asia, especially in southern China, have “integrated” farms. Crops are grown to feed pigs and ducks, and the feces from the pigs and ducks are used to fertilize fish ponds. This is a very efficient farming practice, but, unfortunately, it also places ideal mixing vessels for flu viruses (pigs) in close proximity to humans and ducks.
If a human is infected by a hybrid virus, the immune system (must/can) start from scratch, selecting out entirely new lines of B cells and T cells to attack the intruder. But in the meantime, the virus multiplies so rapidly that many individuals die or become so weakened that they contract some other fatal disease. Other individuals recover, with immune systems now primed to resist any further assault from the new virus. In subsequent years, a few point mutations (can/might) allow a slightly altered strain of the new virus to infect millions of people, but with a partial immune response ready, few fatalities occur. Once again, for most of us, the flu becomes a routine annoyance. At least until the next time the improbable happens again.
II. Find in the text English equivalents to the following Russian words and word combinations:
· проносится по миру
· причиной гриппа являются
· внедряются в клетки дыхательных путей
· внешняя поверхность
· распознаются иммунной системой
· удивительная способность
· отсутствуют механизмы исправления ошибок (при копировании матрицы)
· получает некую точку опоры в теле
· совершенно новые вирусы гриппа
· никогда ранее не сталкивалась
· поразительно похожие
· по крайней мере, мы так полагаем
· необходимые для разрушения
· совершенно новые линии
· готовые теперь к отражению новых атак
· слегка измененный штамм
III. The essay states that the flu virus is different each year. If that is true, what good is it to get a “flu shot” each winter?
Render in English.
Определены место рождения и возраст вируса птичьего гриппа
Место происхождения вируса птичьего гриппа H5N1 - юго-восток Китая. Основной механизм его распространения - перевозка домашней птицы. Однако в некоторых случаях переносить заболевание могут и перелетные птицы. Эти выводы получены в результате анализа десятков тысяч генетических проб, взятых у птиц в течение полутора лет. Группа И Гуаня (Yi Guan) из Университета китайского города Шаньтоу (Shantou) совместно с коллегами из Гонконга проанализировала образцы, взятые у 13 тысяч перелетных птиц и 50 тысяч домашних птиц на рынках в юго-восточных провинциях Китая. Около 2% внешне здоровых домашних уток и гусей оказались носителями вируса H5N1. Среди кур вирус встречался гораздо реже, тем не менее, практически каждый месяц исследователи выявляли зараженных кур. Забор образцов производился с января 2004 по июнь 2005 года, когда китайское правительство запретило независимым исследователям брать анализы у птиц. Хотя новые образцы поступать перестали, собранного материала оказалось достаточно, чтобы сделать целый ряд интересных выводов. Геном вируса в китайских провинциях Гуандун (Guangdong), Хунань (Hunan) и Юньнань (Yunnan) демонстрирует наибольшие генетические вариации по сравнению с другими территориями. Разные версии вируса образуют географические кластеры. Однако все версии эволюционно восходят к гуандунскому вирусу 1996 года. Все это говорит о том, что в данном районе вирус появился раньше, чем в других, и не менее 10 лет назад. В то же время, само наличие географических кластеров с генетически различными линиями вируса указывает на то, что инфекция редко переносится птицами, совершающими дальние перелеты. Большая часть заражений происходит при перевозке домашней птицы. Тем не менее, в некоторых случаях переносчиками заболевания могут быть и перелетные птицы. Например, в январе-марте 2005 года в образцах, взятых у диких уток на озере Поян (Poyang) в провинции Цзянси (Tzyansi), граничащей с Гуандуном и Хунанем, была найдена особая форма одного из генов. Позднее, при вспышке эпидемии в Турции, у вируса обнаружился такой же ген, что говорит о практически прямом переносе вируса на значительные расстояния.
Unit 12
Animal Behaviour
Introduction
I. Check if you know the following words:
innate behaviour extensive designated appropriate random
elicit stimuli modify input response withdrawal
Listen to the text and determine the differences of innate and learned behaviour.
II. Try to apply the concepts stated and answer the following questions:
1. You are a police officer; your new partner is a German shepherd, which you are assigned to train as a narcotics dog. You plan to use motivational techniques rather than negative reinforcement. Which behaviour principles (processes) would you use in your training? What are the advantages of positive over negative reinforcement?
2. Your 3-year-old child persistently approaches the hot stove even though you have told her not to touch it. Which type of learning is she attempting to use? Is there any other learning process that might work that would not require her to touch the hot stove?
Reading
Read and translate the following text.
Robot cricket finds her mate
The cheerful chirping of a cricket is actually the “call song” of the male as he attempts to attract a female. The female follows the song unerringly, deftly detouring around obstacles and ignoring other sounds en route to her prospective mate. How intelligent is this apparently purposeful behaviour? Barbara Webb, a psychologist at the University of Edinburgh, Scotland, attacked this problem in an novel way; she built a robot female cricket. Webb’s goal was to find out whether mate-finding behaviour could be distilled down to taxes, relatively simple responses to stimuli, such as responses that could be wired into an electronic robot (and thus wired into genetically predetermined neural connections). Although its tangle of wires appears bewildering, the circuitry of the robot is trivial when compared with the potential complexity of neural connections – even in a cricket’s brain.
On the laboratory bench, a loudspeaker “male cricket” broadcasts its species-specific call song: short, regularly repeating tones. As the robot rolls forward, microphonic ears conduct the song to electronic circuitry that filters it from other sounds and adds together the repeating syllables of the song that reach each ear. The summed sounds in the ear closest to the loudspeaker reach a critical threshold level first, activating a mechanism that turns the robot toward the sound. The turning halts when an equal intensity of sound hits both ears. Sensory “bumpers” help the robot detour around obstacles. The success of “robocricket” surpassed Webb’s expectations; it not only found its “mate” but it unexpectedly mimicked other cricket-searching behaviours. Placed between two loudspeakers that broadcast at equal volume, the robot, like a real cricket, arbitrarily chose one speaker. If the repeating syllables of the song were altered between the two speakers, the robot (again, like a real cricket) first positioned itself exactly between them, then made an arbitrary choice. The electronic circuitry provides insights into mechanisms that could be used by a simple nervous system to produce complex adaptive behaviour.
Language focus 1
Conditionals 1, 2 and 3
1 Conditional sentences are formed as follows:
Type 1: if + present tense, present tense or modal
I am sure you’ll understand the situation if I explain it to you.
If the scientist succeeds in confirming his repeated observations, it may be stated that an empirical law or rule of nature has been discovered.
Type 2: if + past tense, would/could + verb
If we didn’t invite the rest of the group to the party, they would feel hurt.
Could this method be approached from a historical point of view if we gave a brief account of the development of concepts and theories involved?
Type 3: if + had + past participle of verb, would/could have + past participle of verb: If we had known about the problem, we would have done something.
2 Conditional type 1 has the following uses:
- cause and effect
If you criticize people, you’ll kill their creativity.
Students work harder if you motivate them.
- predict consequences of likely situations
We will fail to be on time if we don’t follow his advice.
- request action in the event of a likely situation
Tell me if you get any new ideas.
Let me know if you need additional data.
3 Conditional type 2 has the following uses:
- predict consequences of unlikely situations
If the grant were received, we would have the money to expand.
- talk about unreal and hypothetical situations
If we had more time, we’d be able to work more effectively.
4 Conditional type 3 has the following uses:
- evaluate or analyse past actions
If we’d made the decision sooner, we could have saved a lot of money. (= We should have decided sooner.)
- talk about hypothetical situations in the past
If we had had a different idea, we’d have been able to calculate the result of an experiment in a shorter time.
I. Write the verbs in the appropriate form to make a conditional sentence with the meaning that is given in brackets.
1. I (invite) _________ you for dinner if I (know) _________ you were free. (hypothetical situation in the past)
2. If the experiment (be conducted) _________ earlier, we (have) _________ the results now. (hypothetical)
3. If we (increase) _________ the data volume, we (improve) _________ the validity of the research. (cause and effect)
4. If man (not develop) _________ his large brain, some other mammal, perhaps, the raccoon, (do) _________ so in a few tens of millions of years. (hypothetical situation in the past)
5. Our colleagues (get) _________ the grant if they (submit) _________ all necessary documents before the deadline. (predicting likely situation)
6. Just (send) _________ me an email if you (have) _________ any problems. (request)
7. It (be) _________ better if we (be) _________ honest about the situation with samples. (tentative suggestion)
8. If we (fail) _________ to complete the study on time, we (have to) _________ miss the conference. (unlikely situation)
9. If we (install) the software last year, we (do) _________ the research. (analyse past actions)
10 If he (go) _________ to university, he (get) _________ a better job. (hypothetical situation in the past)
Words, Words, Words
Complete the abstract with the correct option A-C. Consult the dictionary if necessary.
Animals May Defend Territories that Contain Resources
In many animal (1) ______, (2) ______ for (3) ______ takes the form of territoriality, the defense of an area where important resources are located. The (4) ______ resources may include places to mate, raise young, feed, or store (5) ______. Territorial animals generally (6) ______ most or all of their activities to the defended area and (7) ______ their presence there. Territories may be defended by males, females, a mated pair, or entire social groups (as in the case of defense of their nest by social insects). However, territorial behaviour is most commonly seen in adult males, and territories are normally defended against members of the same species, who compete most directly for the resources being protected. For example, they can be a tree where a woodpecker stores acorns, small (8) ______ in the sand used as nesting sites by cichlid fish, a hole in the sand used as a home by a crab, or an area of forest (9) ______ food for a squirrel.
(10) ______ and defending a territory require considerable time and energy, yet territoriality is seen in animals as diverse as worms, arthropods, fish, birds, and (11) ______. The fact that organisms as unrelated as worms and humans independently (12) ______ similar behaviour suggests that territoriality provides some important (13) ______ (14) ______. Although the particular benefits depend on the species and the type of territory it defends, some broad generalizations are possible. First (as with dominance hierarchies), once a territory is established through aggressive interactions, relative peace (15) ______ as boundaries are recognized and respected. The saying “good fences make good neighbours” also applies to nonhuman territories. One reason for this (16) ______ is that an animal is highly motivated to defend its territory and will often defeat even larger, stronger animals that attempt to invade it. (17) ______, an animal outside its territory is much less secure and more easily defeated.
For males of many species, successful territorial defense has a direct impact on reproductive success. In these species, females are attracted to a high-quality (18) ______ territory, which might have features such as large size, (19) ______, food, and secure nesting areas. Males who successfully defend the most desirable territories have the greatest chance of mating and passing on their genes. For example, experiments have shown that male sticklebacks that defend large territories are more successful in (20) ______ mates than are males who defend small territories. Females who select males with the best territories increase their own (21) ______ success and pass their genetic traits (typically including their mate-selection preferences) to their offspring.
Territories are advertised through (22) ______, sound, and (23) ______. If the territory is small enough, the owner’s mere presence (24) ______ by aggressive displays at (25) ______, can be a (26) ______ defense. A mammal that owns a territory but cannot always be present may use pheromones to scent-mark its terrestrial boundaries. Male rabbits use pheromones secreted by glands in their chin and by anal glands to mark their territories. Hamsters rub the areas around their (27) ______ with secretions from special glands in their glands.
1 A specimen B species C samples
2 A competence B competition C competency
3 A resources B reserves C supply
4 A defended B defeated C deseeded
5 A meal B nourishment C food
6 A restrict B refrain C restore
7 A advise B adverse C advertise
8 A destinations B depressions C degressions
9 A supplying B procuring C providing
10 A Acquiring B Requiring C Requiting
11 A mammas B mammoths C mammals
12 A evoked B evolved C involved
13 A adaptive B adoptive C abortive
14 A disadvantages B disabilities C advantages
15 A prevails B prevents C prewires
16 A aspect B extent C respect
17 A Inversely B Conversely C Diversely
18 A breeding B blooming C brooding
19 A abundant B redundant C excessive
20 A detracting B attracting C attributing
21 A creative B productive C reproductive
22 A seeing B sight C vision
23 A smell B scent C fragrance
24 A force B enforce C reinforce
25 A interveners B intruders C interrupters
26 A sufficient B suffocating C suffruticose
27 A fangs B teeth C dens
Language focus 2
“I Wish” Sentences
We use wish to say that we regret something, that something is not as we would like it to be:
I wish he would take part in the project. = I want him to take part in the project.
I wish he took part in the project. = He is not taking part in the project and I regret that.
I wish he had taken part in the project. = He didn’t take part in the project, I can’t change anything.
I. Choose the verbs in the appropriate form.
1. I wish I _________ a computer. It would make life so much easier.
A have B had C would have
2. I feel so tired. I wish I _________ less today.
A had worked B worked C work
3. I wish it _________ summer now.
A were B had been C is
4. I wish it _________ stop snowing.
A stops B stopped C would stop
5. I wish they _________ part in the competition but they refused.
A would take B took C had taken
6. I wish I _________ more friends.
A have B had C would have
7. I wish I _________ here. It is so noisy and boring here.
A don’t come B hadn’t come C didn’t come
II. Translate sentences into English.
1. Если ты встретишь Петра, тебе следует попросить у него прощения.
2. Жаль, что вы не хотите сосредоточить свое внимание на одной задаче.
3. Желательно, чтобы эти эксперименты были проведены до начала новой серии опытов.
4. Если бы он согласился на изменение условий эксперимента, успех был бы гарантирован.
5. Я был бы очень благодарен, если бы вы прислали мне эти материалы как можно скорее.
6. Человек может достигнуть исключительных результатов, если его воодушевляет высокая цель.
7. Если бы проверка была проведена вовремя, были бы исключены случайные ошибки и были бы получены надежные результаты.
8. Теория была бы принята большинством ученых, если бы мы предоставили новые доказательства в ее поддержку.
9. Жаль, что так мало внимания уделяется сравнению экспериментально полученных результатов с результатами, предсказанными теоретически.
10. Если используется новая методика, специально разработанная для данного эксперимента, подобные недостатки легко преодолеть.
Render in English
Игры животных: почему и зачем?
Что такое игра? Четкого определения игры до сих пор нет, хотя все понимают, о чем идет речь. Невозможно не любоваться играющими щенками или котятами. Игра - поведение типичное для развивающегося организма. Для некоторых животных точно определен возраст, когда они играют. Например, у лабораторных крыс игровое поведение наблюдается с 22-24 дня по 60 день жизни, у хомяков - с 28 дня по 58-68. Часто игру начинает взрослое животное (мать): львица побуждает львят ловить кончик ее хвоста, обезьяны поворачивают на спину и щекочут своих малышей, кошки, вылизывая котят, затевают с ними борьбу.
В играх различных животных можно выделить общие признаки.Движения в игре не отличаются от тех, которые встречаются в иных ситуациях: охота, умерщвление добычи, драка, погоня, половая активность. Наблюдая за игрой котенка с клубком шерсти, нельзя не увидеть сходства с охотой на мышей, а прыжки и движения лап при ловле подвешенной на нитке бумажки такие же, как при охоте взрослой кошки на птиц. К. Лоренц описывает, как взрослая кошка защищает своих котят от собаки: она идет на нее характерным боковым движением на вытянутых лапах, взъерошив шерсть и распушив хвост. Подобные характерные передвижения боком часто можно наблюдать у играющих котят, но они никогда не используются в драке взрослых кошек. Несмотря на имитацию охоты или драки, животные не наносят друг другу серьезного вреда. В игре часто сочетаются элементы разных типов поведения, не связанных между собой во взрослой жизни, например, охотничье и половое. Порядок, с которым движения следуют друг за другом, также может не соответствовать поведению взрослого животного, а иногда быть прямо противоположным. Элементы игры бывают преувеличены, многократно повторяются, но часто не завершаются. Обычно животное подает сигнал о том, что оно собирается начать игру. У макак-резусов это "игровая мимика", у кошек и собак - припадание на грудь и передние лапы. Иногда в игре животное использует совершенно новое движение, которое не встречается у взрослых животных. Описано игровое сальто у ручного барсука и кувырок через голову с изменением маршрута у щенка, убегавшего от матери. Игровое поведение легко прерывается, и животное возвращается к обычной жизни.
Ученые пришли к выводу, что в основе игрового поведения лежит мотивация, отличная от мотивации того поведения, которое изображается в игре (в охоте - мотивация голода, в половом поведении - мотивация продолжения рода и т. д.). Мотивация, которая лежит в основе игры, настолько сильная, что может конкурировать с другими желаниями животного. Например, молодая самка шимпанзе, которую не кормили в течение 15 часов, в 40% случаев выбирала игру с другими обезьянами, а не пищу.
Зачем нужна игра? Прежде всего, игра - это тренировка для развития мышечной, опорно-двигательной, дыхательной, сердечно-сосудистой и нервной систем. Она способствует увеличению мышечной массы, массы сердца, плотности капиллярного русла, повышению жизненной емкости легких, скорости роста организма. Игра знакомит молодое животное с окружающей средой. Котенок, играющий с клубком шерсти, начинает понимать, что не все маленькие, мягкие, быстро передвигающиеся предметы съедобны, как мыши. Лишение животного возможности играть имеет далеко идущие последствия. Макака резус, выросшая изолированно от других обезьян с манекеном матери, не умела впоследствии играть со сверстниками, устанавливать нормальные отношения с сородичами и в дальнейшем - спариваться. Сложности в период полового поведения наблюдали и у собак, выросших без общения с другими собаками. Отдельные элементы полового, охотничьего поведения отрабатываются в играх детенышей еще до наступления половой зрелости, поэтому развитие поведения носит опережающий характер.
Исследование энергетического обмена организма выявило обратную зависимость между уровнем обмена веществ в покое и игровой активностью. Так что игра восполняет дефицит энергетических затрат организма в молодом возрасте.
Изучение активности нервных клеток теменной области коры мозга показало, что их способность отвечать на несколько раздражителей (свет, звук, прикосновение к коже) возрастает от 6 % клеток у 8-10 дневных котят до 89 % у 49-50 дневных, то есть совпадает с развитием игрового поведения. Следовательно, игра необходима для развития не только телесных, но и мозговых структур организма.
Приложение
Unit 1
Life and Levels of Organization of Living Matter
Listening
Life
All of us have an intuitive understanding of what it means to be alive. However, defining life is difficult, partly because living things are so diverse and non-living matter looks like life in some cases. What’s more, living things cannot be described as the sum of their parts. The quality of life emerges as a result of incredibly complex, ordered interactions among these parts. Among the characteristics of living things that, taken together, are not shared by non-living things are the following: living things consist of organic molecules, they acquire and use materials and energy from their environment and convert them into different forms, they grow and reproduce.
Unit 2
Biological Molecules
Protein Structure – a Hairy Subject
A single strand of human hair, thin and not even alive, is nonetheless a highly organized, complex structure. Hair is composed mostly of a single, helical protein called keratin. If we look closely at the structure of hair, we can learn a great deal about biological molecules, chemical bonds, and why human hair behaves as it does.
A single hair consists of a hierarchy of structures. The outermost layer is a set of overlapping shingle-kike scales that protect the hair and keep it from drying out. Inside the hair lie closely packed, cylindrical dead cells, each filled with long strands called microfibrils. Each microfibril is a bundle of protofibrils, and each protofibril contains helical keratin molecules twisted together. As a hair grows, living cells in the hair follicle embedded in the skin whip out new keratin at the rate of 10 turns of the protein helix every second.
Pull the ends of a hair, and you will notice that it is rather strong. Hair gets its strength from three types of chemical bonds. First, the individual molecules of keratin are held in their helical shape by many hydrogen bonds. Before a hair will break, all the hydrogen bonds of all the keratin molecules in one cross-sectional plane of the strand must break to allow the helix to be stretched to its maximal extent. Second, each molecule is cross-linked to neighboring keratin molecules by disulfide bridges between cysteines (particular amino acids). Some of these bridges must break as the hair stretches. Finally, at least one peptide bond in each keratin molecule must break the strand as a whole breaks.
Hair is also fairly stiff. The stiffness arises from hydrogen bonds within the individual helices of keratin molecules together. When hair gets wet, however, the hydrogen bonds between turns of the helices are replaced by hydrogen bonds between the amino acids and the water molecules surrounding them, so the helices collapse. Wet hair is therefore very limp. If wet hair is rolled onto curlers and allowed to dry, the hydrogen bonds re-form in slightly different places, holding the hair in a curve. The slightest moisture, even humid air, allows hydrogen bonds to rearrange into their natural configuration, and normally straight hair straightens out.
Pull gently, and you will discover still another property of hair. It stretches and then springs back into shape when you release the tension. When hair stretches, many of the hydrogen bonds within each keratin helix are broken, allowing the helix to be extended. Most of the covalent disulfide bonds between different levels of the helices, in contrast, are distorted by stretching but do not break. When tension is released, these disulfide bridges contract, returning the hair to its normal length.
Finally, each hair has a characteristic shape: It may be straight, wavy, or curly. The curliness of hair is genetically specified and is determined biochemically by the arrangement of disulfide bridges. Curly hair has disulfide bridges cross-linking the various keratin molecules at different levels, whereas straight hair has bridges mostly at the same level. When straight hair is given a “permanent”, two lotions are applied. The first lotion breaks disulfide bonds between neighboring helices. The hair is then rolled tightly onto curlers, and a second solution, which re-forms the bridges, is applied. The new disulfide bridges connect helices at different levels, holding the strands of hair in a curl. These new bridges are more or less permanent, and genetically straight hair can be transformed into biochemically curly hair. As new hair grows in, it will have the genetically determined arrangement of bridges and will not be curly.
Unit 3
Energy Flow in the Life of a Cell
Introduction
Listen and answer the questions.
1. What is caused within a system by any use of energy (according to the second law of thermodynamics)?
2. How does energy flow in chemical reactions?
3. Give an example of an exergonic reaction.
4. How is cellular energy carried between coupled reactions?
The flow of energy among atoms and molecules obeys the laws of thermodynamics. The first law of thermodynamics states that, assuming there is no influx of energy, the total amount of energy remains constant, although it may change in form. The second law of thermodynamics states that any use of energy causes a decrease in the quantity of concentrated, useful energy and an increase in the randomness and disorder of matter. Entropy is a measure of disorder within a system.
Chemical reactions fall into two categories. In exergonic (Greek for “energy out”) reactions, the product molecules have less energy than do the reactant molecules, so the reaction releases energy. In endergonic (Greek for “energy in”) reactions, the products have more energy than do the reactants, so the reactions can occur spontaneously, but all reactions, including exergonic ones, require an initial input of energy (the activation energy) to overcome electrical repulsions between reactant molecules. Exergonic and endergonic reactions may be coupled such that the energy liberated by an exergonic reaction drives the endergonic reaction. Organisms couple exergonic reactions such as light-energy capture or sugar metabolism with endergonic reactions such as synthesis of organic molecules.
Energy released by chemical reactions within a cell is captured and transported about the cell by energy-carrier molecules such as ATP and electron carriers. These molecules are the major means by which cells couple exergonic and endergonic reactions that occur at different places in the cell.
Unit 4
Principles of Evolution
Introduction
Listen to a brief biography of a very famous scientist. A student first to say the scientist’s name will win the contest.
1. The son of a country parson who greatly loved flowers, in his youth he set himself the task of establishing new system for describing and ordering animals, plants and minerals.
2. He studied at the university in Lund, Uppsala and in Harderwijk, Holland, where he obtained his M.D.
3. In Holland worked as superintendent of George Clifford's botanical garden near Harlem; published Systema Naturae, presenting his new system of taxonomy.
4. Having returned to his motherland, he was appointed a physician to the admiralty, helped to found the Academy of Science, became a professor of medicine at the University of Uppsala;
5. Renovated the university's botanical garden, where he lived for the rest of his life; was elevated to the nobility.
6. Brought an urgently needed simplicity to the classification of plants; worked out a sexual system, grouping plants in classes, according to the number and order of stamens, and then into orders, mostly according to the number of pistils; although he realized that this was an artificial structure, he did not fully work out a more "natural" system;
7. Was the first to work with species as a clearly defined concept;
8. Introduced binomial nomenclature based on genus and species; concluded that for every natural plant order, only one species had been created originally.
9. Published his most influential work Philosophia botanica (an expansion of Fundamental botanica)in 1751.
10. In Species plantarum he described about 8000 plant species; his definitive 10th edition of Systema naturae appeared in 1758-59.
11. In Oeconomica naturae he developed concepts of the balance and competition in nature among the insects, animals and plants.
12. Was less influential in the classification of the animal and mineral kingdoms but did group man with the apes, and was the to recognize whales as mammals; his insect orders are still recognized.
Based on the Concise Dictionary of Scientific Biography 2000 New York
Answer: Linneus (or von Linne), Carl.
Unit 5
The History of Life on Earth
Introduction
Listen to the account of the history of ideas concerning the generation of life on Earth and discuss in pairs whether the following sentences are true or false.
How and when did life first appear on Earth? Just a few centuries ago, this question would have been considered trivial. Although no one knew how life first arose, people thought that new living things appeared all the time, through spontaneous generation from both nonliving matter and other, unrelated forms of life. In 1609, a French botanist wrote, “There is a tree… frequently observed in Scotland. From the tree leaves are falling: upon one side they strike the water and slowly turn into fishes, upon the other they strike the land and turn into birds.” Medieval writings abound with similar observations and delightful recipes for creating life – even human beings. Microorganisms were thought to arise spontaneously from broth, maggots from meat, and mice from mixtures of sweaty shirts and wheat.
In 1668 the Italian physician Francesco Redi disproved the maggots-from-meat hypothesis simply by keeping flies (whose eggs hatch into maggots) away from uncontaminated meat. Then in the mid-1800s, Louis Pasteur in France and John Tyndall in England disproved the broth-to-microorganism idea. Although their work effectively demolished the notion of spontaneous generation, it did not address the question of how life on Earth originated in the first place.
For almost half a century, the subject lay dormant. Eventually, biologists returned to the question of the origin of life and began to seek answers. In the 1920s and 1930s, Alexander Oparin in Russia and John B. S. Haldane in England noted that the oxygen-rich atmosphere that we know would not have permitted the spontaneous formation of the complex organic molecules necessary for life. Oxygen reacts rapidly with other molecules, disrupting chemical bonds and thus tending to keep molecules simple. Oparin and Haldane speculated that the atmosphere of the young Earth was very low in oxygen and rich in hydrogen in the form of hydrogen gas (H2), methane (CH4), and ammonia (NH3). Given these and other conditions Oparin and Haldane proposed that life could have arisen from nonliving matter through ordinary chemical reactions. This process is called chemical evolution, or prebiotic evolution: that is, evolution before life existed.
1. Several centuries ago no one thought it difficult to answer the question of how living things had arisen. T
2. Earlier people thought that life had appeared spontaneously from nonliving things and other forms of life. T
3. In Medieval texts the authors suggested ways of creating nonliving things from living things. F: “Medieval writings abound with similar observations and delightful recipes for creating life – even human beings”
4. People thought that microorganisms had arisen from broth and wheat. F: “Microorganisms were thought to arise spontaneously from broth, maggots from meat, and mice from mixtures of sweaty shirts and wheat.”
5. Francesco Redi proved that maggots did not arise from rotting meat. T
6. Louis Pasteur’s ideas did not answer the question of how life on Earth had originated. T
7. Alexander Oparin thought that complex organic molecules could be formed spontaneously only if oxygen was around. F: “Alexander Oparin in Russia and John B. S. Haldane in England noted that the oxygen-rich atmosphere that we know would not have permitted the spontaneous formation of the complex organic molecules necessary for life.”
8. Oxygen keeps molecules simple. T
9. Oparin and Haldane argued that the primordial atmosphere consisted of hydrogen gas, methane and free oxygen. F: “Oparin and Haldane speculated that the atmosphere of the young Earth was very low in oxygen and rich in hydrogen in the form of hydrogen gas (H2), methane (CH4), and ammonia (NH3).”
10. Prebiotic evolution means evolution of nonliving matter to become living matter. T
Unit 6
Biotechnology
Introduction
Listen to the abstract and compare the answers with your ideas:
- What is a definition of biotechnology?
- What are goals of genetic engineering?
In its broadest sense, biotechnology is defined as any industrial or commercial use or alteration of organisms, cells, or biological molecules to achieve specific practical goals. By this definition, biotechnology is nothing new – it is as old as the use of yeast to make bread rise or to ferment grape juice into wine, a process that originated 10,000 years ago. It is as old as selective breeding of plants and animals in agriculture. Squash fragments preserved in a dry cave in Mexico were recently dated as 8000-10,000 years old. Their seeds are larger and their rinds thicker and more colorful than those of wild varieties, providing evidence or selective breeding – a very early form of genetic manipulation by humans. Prehistoric art and animal remains suggest that dogs, sheep, goats, and camels were domesticated 10,000 – 12,000 years ago.
Modern biotechnology commonly utilizes genetic engineering, the modification of genetic material to achieve specific goals. Genetically engineered cells may have genes deleted, added, or replaced. The major goals of genetic engineering are threefold:
1.to understand more about the processes of inheritance and gene expression;
2.to provide better understanding and treatment of various diseases, particularly genetic disorders, and
3.to generate economic benefits, including improved plants and animals for agriculture and efficient production of valuable biological molecules.
Unit 7
The Double Helix
Introduction
Listen to the text “Red Bread Mold Provided Insight into the Role of Genes”. Say whether the following statements are true or false.