Life and Levels of Organization of Living Matter
Introduction
This is a test similar to the Final Test at the end of the third year at the Faculty of Biology, though it has been shortened for convenience. It is aimed at revealing which areas of language you still need to work at.
Listening Task
You will hear a short extract about life. It will be read twice. Answer the following questions:
1. Why is it difficult to define life? (Give at least two reasons.)
2. What are the characteristics of living matter? (Name at least three.)
Translation Task
Using your dictionary, translate the following:
The quality of life emerges on the level of the cell. Just as an atom is the smallest unit of an element, so too the cell is the smallest unit of life. The difference between a living cell and a conglomeration of chemicals illustrates some of the emergent properties of life.
Fundamentally, all cells contain genes, units of heredity that provide the information needed to control the life of the cell; subcellular structures called organelles, these being miniature chemical factories that use the information in the genes and keep the cell alive; and a plasma membrane, a thin sheet surrounding the cell that both encloses a watery medium (the cytoplasm) that contains the organelles and separates the cell from the outside world. Some life-forms, mostly microscopic, consist of just one cell, but larger life-forms are composed of many cells whose functions are differentiated. In these multicellular life-forms, cells of similar type are combined into tissues, each performing a particular function. Various tissue types combine to make up a structural unit called an organ. Several organs that collectively perform a single function are called an organ system, and all the organ systems functioning cooperatively make up an individual living thing, the organism.
Rendering Task
At the exam you will be asked to render a Russian article (about a page long) into English. The task has to be done very fast. Render the following extract from a Biology textbook into English. Summarize, do not try to translate word-by-word. Use Vocabulary at the end of the text. (You do not have to use all the words!)
Клетка – структурная и функциональная единица, а также единица развития всех живых организмов, обитающих на Земле. На клеточном уровне сопрягаются передача информации и превращение веществ и энергии.
Элементарной единицей организменного уровня служит особь, которая рассматривается в развитии – от момента рождения до прекращения существования – как живая система. На этом уровне возникают системы органов, специализированные для выполнения различных функций.
Совокупность организмов одного и того же вида, объединенная общим местом обитания – это надорганизменная система, называемая популяцией. В этой системе осуществляются элементарные эволюционные преобразования – процесс микроэволюции.
Сообщество – совокупность организмов разных видов и различной сложности организации с факторами среды их обитания. В процессе совместного исторического развития организмов разных систематических групп образуются устойчивые сообщества.
Биосфера, наконец – это совокупность всех сообществ, система, охватывающая все явления жизни на нашей планете. На этом уровне происходит круговорот веществ и превращение энергии, связанные с жизнедеятельностью всех живых организмов.
Vocabulary:
наследственная информация – hereditary information
превращение веществ и энергии – conversion of matter and energy
особь – an individual
место обитания – a habitat
популяция – a population
эволюционные преобразования – evolutionary transformations
сообщество – a community
сложность организации – the complexity of organization
биосфера – the biosphere
круговорот веществ – the flow of matter
Language Focus 1
Passive Voice
1 Compare:
- They built this house in 1887 (active).
This house was built in 1887 (passive).
- This thing will change your life (active).
Your life will be changed by this thing (passive).
When A does something to B, there are often two ways to express it. If we want A (doer) to be the subject, we use an active verb: built, will change. If we want B (the “receiver” of the action) to be the subject, we use: was built, will be changed.
In most cases, the subject of an active verb is not expressed in the corresponding passive sentence. If it does have to be expressed, this usually happens in an expression with by; the noun is called the ‘agent’.
This house was built in 1887 by Sir George Green.
2 We often choose passive structures when we want to talk about an action, but are not so interested in saying who or what does/did it. Passives without ‘agents’ are common in academic and scientific writing for this reason.
The laboratories are very well equipped nowadays.
3 We often prefer to begin a sentence with something that is already known, or that we are already talking about, and to put the ‘news’ at the end. This is another common reason for choosing passive structures. Compare:
Tom is completing his diploma paper. (Active verb so that the ‘news’ – the diploma paper – can go at the end.)
Great experiment! – Yes, it was completed by our young scientists. (passive verb so that the ‘news’ – our young scientists – can go at the end)
Passive Voice: Tense Forms
Fill in the table with forms of verbs in the Passive Voice:
| Present Simple …. / is /….trusted Past Simple ….. / ..… obtained Future Simple ….. ..… held Present Perfect ….. / has ….. …… Past Perfect ….. ….. ………. Future Perfect ….. ….. been … | Present Continuous ….. / .. / ..… …… ..…. Past Continuous ….. / ..… being …... Perfect Continuous have /… …... …. studied |
I. Split into pairs. Complete the sentences with any possible endings.
1. The necessary substance is being (has been) obtained …
2. The lecture will be (will have been) presented to 400 students of all years …
3. The meeting was being (had been) held in the Main Building of MSU …
4. The calculations of the shuttle’s movement have not been (are not being) corrected …
II. Form groups of four. The first student reads the beginning of the sentence; the rest give their variants of its end.
1) A new shopping centre has recently been built in the neighbourhood …
2) Two atomic power stations are being put into operation near Moscow these days..
3) Sample collection will have been completed by today’s evening …
4) When the accident happened, I was being shown the building …
III. Think of your own beginnings and continuations. Use the Passive Voice in the beginnings.
Words, Words, Words
I. Compose three sentences which would include all the words and word
combinations below. Please pay attention to the Usage Box below. You can use the constructions given there.
hereditary information an individual
the biosphere population
microscopic and multicellular life-forms
subcellular structures non-living matter
II. In pairs, group these words according to any chosen criterion.
Grammar Review
I. Translate into English using passive constructions.
1. Многое было сделано для развития биологической науки в современной России.
2. В этой лаборатории за последнее время было реализовано только два исследовательских проекта.
3. Расчеты собираются завершить на этой неделе.
4. Необходимую информацию скоро предоставят.
5. Печень может одновременно выполнять две функции.
6. На следующем уровне организации клетки объединяются в ткани.
7. Cегодня были отправлены новые данные.
8. Зеленые растения получают энергию в процессе фотосинтеза.
9. Врачу необходимо доверять.
II. Think of sentences that would include the following words and word combinations:
a. ... being tested … b. … been provided …
c. … am trusted … hurt … d. … to be obtained …
e. … should be put into … f. … was presented …
g. … will … performed …
Language focus 2
|
I. Find it+passive constructions in this extract. Can you think what they serve for grammatically and stylistically?
It is generally agreed that the more difficult it is to follow the lecture, the more easily we get obsessed by sleep or other pleasant activity apart from listening to the professor. It has been observed that the farther you are from the source of noise, the more you are prone to sleepiness. It is thought that this phenomenon develops due to the fact that the sound vibrations produced by the professor’s articulative organs affect the auditory receptors of the nearby listeners stronger, resulting in more vivacity and higher speed of writing.
II. Include it-constructions given here in one of the articles below (you may choose any). Mind the tense of the passive!
 | |||||||||||||
 |  | ||||||||||||
| |||||||||||||
 | |||||||||||||
 | |||||||||||||
 |
A Organisms can be grouped into three major categories, called domains: (1) Bacteria, (2) Archaea [a:¢kı(:)ə], and (3) Eukarya [ju¢kærıə]. This classification is based on fundamental differences among the cell types that comprise these organisms. Members of both the Bacteria and the Archaea normally consist of single, simple cells. Members of the Eukarya have bodies composed of one or more highly complex cells and are subdivided into four kingdoms: Protista, Fungi [¢fΛndзı], Plantae, and Animalia. There are exceptions to any simple set of criteria used to characterize the domains and kingdoms, but three characteristics are particularly useful: cell type, the number of cells in each organism, and the mode of nutrition – that is, energy acquisition.
| B |
There are two fundamentally different types of cells: (1) prokaryotic and (2) eukaryotic. Kariotic refers to the nucleus of a cell; eu means “true” in Greek; eukaryotic cells possess a “true”, membrane-enclosed nucleus. Eukaryotic cells are larger than prokaryotic cells and contain a variety of other organelles, many surrounded by membranes. Prokaryotic cells do not have a nucleus; their genetic material resides in their cytoplasm. They are small – only 1 or 2 micrometers long – and lack membrane-bound organelles. Pro means “before” in Greek; prokaryotic cells almost certainly evolved before eukaryotic cells (and eukaryotic cells probably evolved from prokaryotic cells). Bacteria and Archaea consist of prokaryotic cells; the cells of the four kingdoms of Eukarya are eukaryotic.
| C |
All organisms need energy to live. Photosynthetic organisms capture energy from sunlight and store it in molecules such as sugars and fats. These organisms, including plants, some bacteria, and some protists, are therefore called autotrophs, meaning “self-feeders”. Organisms that cannot photosynthesize must acquire energy prepackaged in the molecules of the bodies of other organisms; hence, these organisms are called heterotrophs, meaning “other-feeders”. Many archaeans, bacteria, and protists and all fungi and animals are heterotrophs. Heterotrophs differ in the size of the food they eat. Some, such as bacteria and fungi, absorb individual food molecules; others, including most animals, eat whole chunks of food and break them down to molecules in their digestive tracts (ingestion).
III. Three tasks presented below are multiple choice tasks. Only one answer in each assignment is correct. Make your choice!
1. A scientist examines an organism and finds that it is eukaryotic, heterotrophic, and multicellular and that it absorbs nutrients. She concludes that the organism is a member of the kingdom:
a. Bacteria
b. Protista
c. Plantae
d. Fungi
e. Animalia
f. Archaea
2. Which statement is correct?
a. Eukaryotic cells are simpler than prokaryotic cells.
b. “Heterotroph” means “self-feeder”.
c. Mutations are accidental changes in genes.
d. A scientific theory is similar to an educated guess.
e. Genes are proteins that produce DNA.
3. Which of the following are characteristics of living things?
a. They reproduce.
b. They respond to stimuli.
c. They are complex and organized.
d. They acquire energy.
e. All of the above.
Language Focus 3
Indirect Passive
1 Some verbs can have two objects (usually a person and a thing):
We gave the professor all the materials. (= We gave all the materials to the professor.)
(Object 1 – the professor (indirect object), object 2 – all the materials (direct object))
So it is possible to make two passive sentences (without or with a preposition):
The professor was given all the materials. or All the materials were given to the professor.
2 Some other verbs that can have two objects are:
ask make pay show tell
bring offer promise take throw
buy pass send teach write
3 When these verbs are used in passive structures, the subject is usually the person who receives something, not the thing which is sent, given, etc.; however, it can be the subject if necessary:
What happened to other books? – Well, an Oxford Russian dictionary was given to Ms Jones.
I. Form the Direct and Indirect Passives where possible. Follow the example given.
Indirect Obj. Direct Obj.
Somebody gave me the book. =>
The book was given to me.
I was given the book.
Not all the verbs can be ‘turned around’ in such a way (e.g. to bring, to send, to take):
Somebody brought a letter to me.
A letter was brought to me.
I was brought the letter.
1. Some university has granted a scholarship to Peter.
A scholarship ………………………………………………………………….……
Peter………………………………………………………………………………….
2. They asked me a lot of questions about my research.
I…….…………………………………………………………………………….…
A lot of questions ………………………………………………………….………
3. They offered the post of rector to Mr Sawyer yesterday evening.
The post of rector …………………….…………………………………….………
Mr Sawyer ……………………………………………………………………..……
4. You should show respect to the police!
Respect ..……………………………...………………………………….……….…
The police …………………………………………………………………..…….…
5. Professor Burne taught us several new methods of genetic research.
We…..…….……………………………………………………………………….
Several new methods ……………………………………………………….………
6. You promised me a dinner!
A dinner .……………………………………………………………………....……
………………………………………………………………………………....……
7. Those scientists do not pay me the rent because they say they are very poor.
The rent ……………..…………………………………………………………....…
…………..…………………………………………………………………………
8. Professor Oliver will read us a part from “Hamlet”.
………………………………………………………………………………………
……………………………………………………………………………………….
9. Somebody lent me a hundred roubles.
……………………………………………………………………………………..
………………………………………………………………………………………
10. Some person sent me a greeting by the Internet.
I…………………………………..…………………………………………………
A greeting ……………..………………………………………………………....…
11. A stranger gave me a bunch of roses.
………………………………………………………………………………………
………………………………………………………………………………………
II. Think of your own examples using these verbs.
Language Focus 4
Prepositional Passive
The objects of prepositional verbs can become subjects in passive structures.
We have looked at the plan carefully. ® The plan has been carefully looked at.
Nobody listens to her. ® She is never listened to.
Note the word order. The preposition cannot be dropped.
I don’t like to be shouted at. (NOT I don’t like to be shouted.)
I. Translate the dialogues. Mind the prepositional verbs. Who are speaking? Act the dialogues in class.
a) - How can this be accounted for?
- We don’t know, sir. Such things have never been dealt with before.
- Is there any authority deserving to be relied upon?
- I am afraid there is none, sir.
b) – There is nothing here to be laughed at!
- Why? This can’t be looked at without a smile.
- You’ve probably found something in this worth being written about?
- To be disapproved of by people like you?.. Well, I am not afraid of it. Not a bit.
c) – Has he been sent for?
- Well, he’s been spoken to.
- And what did he say?
- He said it should be thought of as a slight depression.
- A slight depression! Indeed she’s nearly killed herself! Can he be relied upon?
- I believe not. What should we do?
II. Translate into English.
1. Широко известно, что археобактерии представляют собой отдельный домен (надцарство), как бактерии и эукариоты.
2. Было решено, что одним из критериев, по которым организмы подразделяются на группы, является способ получения энергии, то есть способ питания.
3. Раньше считали, что археобактерии включаются в домен (надцарство) бактерий.
4. Полагают, что прокариотические клетки появились прежде эукариотических.
5. Существует соглашение о том, что домен (надцарство) эукариотов подразделяется на четыре царства: растения, животные, грибы и простейшие.
6. Было установлено, что у прокариотических клеток нет органелл, окруженных мембранами.
7. Было замечено, что некоторые простейшие являются гетеротрофами.
8. Сообщили, что исследуемый организм всасывает питательные вещества.
9. Было предложено назвать тип клеток, содержащих окруженное мембраной ядро, эукариотическими, так как слово kariot обозначает «обладающий ядром».
10. Ходят слухи, что этот новый организм питается солнечной энергией, но при этом не фотосинтезирует.
III. Fill in the gaps with any number of words, word combinations or sentences to get a coherent (связный) text.
I was given ………………………and told ………………… I was not promised …………… but offered ………………………………... It …………………….. . Finally I was sent ………. and told that my problem will be dealt with as soon as they ………………………………
IV. Make up singular-plural pairs and formulate the rules for plural forms of different words of Greek and Latin origin.
species phenomena
vacuum syntheses
criterion axes
helix hypotheses
phenomenon theses
genius crises
momentum species
crisis loci
synthesis criteria
thesis momenta
nucleus quanta
quantum radii
analysis foci
locus nuclei
radius analyses
hypothesis helices
axis maxima
focus genii
maximum vacua
Unit 2
Biological Molecules
Reading
I. Read the text. Some sentences have been taken out of the text and are listed below. Choose the correct sentence (a, b, c, etc) for each gap in the text (1, 2, 3, etc).
…. 1 …. As a result, the bodies of all organisms use the same basic types of molecules. For this reason, humans can obtain nutrients from other organisms, and our bodies, in turn, can become nutrients for other organisms after we die.
…. 2 …. How are these molecules formed? What roles do these biological molecules play in our bodies and in the bodies of plants, insects, and fungi? Here we are talking about the basic types of organic molecules – the carbohydrates [ka:bəu¢haıdreıts], lipids, proteins [¢prəuti:nz], and nucleic acids – that form the basis of life on Earth.
…. 3 …. The term is derived from the ability of living organisms to synthesize and use these molecules. Inorganic molecules include carbon dioxide and all molecules without carbon, such as water.
Although the common structure and function of the types of organic molecules among organisms afford unity, the tremendous range of organic molecules accounts for the diversity of living organisms and for the diversity of structures within single organisms and even within individual cells. This vast array of organic molecules, in turn, is possible because the carbon atom is so versatile. A carbon atom has four electrons in its outermost shell, with room for eight. …. 4 …. They become stable by sharing four electrons with other atoms, forming up to four single covalent bonds or fewer double or triple covalent bonds. Molecules with many carbon atoms can assume complex shapes, including chains, branches, and rings.
Organic molecules are much more than just complicated skeletons of carbon atoms, however. Attached to the carbon backbone are groups of atoms, called functional groups that determine the characteristics and chemical reactivity of the molecules. …. 5 ….
…. 6 ….: (1) the use of the same set of functional groups in virtually all organic molecules in all types of organisms and (2) the use of the “modular approach” to synthesizing large organic molecules.
a) These functional groups are far less stable than the carbon backbone and are more likely to participate in chemical reactions.
b) All of the diverse forms of life, from bacteria to mushrooms to redwood trees to sea urchins to humans, evolved from a distant common ancestor.
c) Therefore, carbon atoms are able to form many bonds.
d) The similarity among organic molecules from all forms of life is a consequence of two main features:
e) What sorts of basic biological molecules make up living things?
f) In chemistry, the term organic is used to describe molecules that have a carbon skeleton and also contain some hydrogen atoms.
II. Give the headline of the extract in one word, as a word-combination and a whole sentence.
Language focus 1
The Use of Passive Structures
I. Explain the reasons for using passive structures in the following text.
Disaccharides Consist of Two Single Sugars linked by Dehydration Synthesis
Monosaccharides, especially glucose and its relatives have a short life span in a cell. Most are either broken down to free their chemical energy for use in various cellular activities or are linked by dehydration synthesis to form disaccharides or polysaccharides. Disaccharides are often used for short-term energy storage, especially in plants. Common disaccharides include sucrose (glucose plus fructose), which you stir into your breakfast coffee; lactose (milk sugar: glucose plus galactose), found in the milk you pour in your coffee; and maltose (glucose plus glucose, which will form in your digestive tract as you break down the starch in the pancakes you may have for breakfast). When energy is required, the disaccharides are broken apart into their monosaccharide subunits by hydrolysis.
II. Say whether the passive or active voice is appropriate in these sentences.
Transform those that you think should be in the passive.
1. Roots and seeds commonly form starch.
2. The saliva enzymes break the pancakes that you chew into component sugars.
3. Some lipids form waterproof coverings on plant and animal bodies.
4. We can classify lipids into three major groups: (1) oils, fats and waxes; (2) phospholipids; and (3) steroids.
5. Protein enzymes guide almost all the chemical reactions that occur inside cells.
6. Nature uses some proteins, such as elastine or keratine, for structural purposes; other proteins for energy and material storage (albumin, casein), transport (hemoglobin) and cell movement.
7. We commonly find twenty amino acids in the proteins of organisms.
Language focus 2
By or With?
We use “by” when we talk about an action – what we do to get a result. We use “with” when we talk about a tool or other object that we use to get a result.
I killed the spider by hitting it.
I killed the spider with a shoe.
‘I got where I am by hard work.’ – ‘No, you didn’t. You got there with your wife’s money.’ …
I. a) Fill in the gaps with by or with.
1 The decision was taken ............... a group of scientists.
2 There is only one way to do it - …………… a needle.
3 A meeting was held …………… the authorities on the central square of the town.
4 The reactions in cells are catalyzed …………… enzymes.
5 You could illustrate your idea …………… a picture.
6 You could illustrate your idea ……………. showing a picture.
b) Use the following word combinations in sentences of your own.
– by the process of photosynthesis – with a dropper
– by a computer – with your friend’s efforts
– by being polite – with that principle
Words, Words, Words
Using the words given, tell the class about:
A Amino acids
a chain a functional group
an amino group a carboxyl group a variable group
to be (in)soluble in water to link together
to differ in properties
B Proteins
highly organized molecules four levels of organization
to assume primary, secondary, tertiary [¢tə:òərı] and quaternary [kwə¢tə:nərı] structures
a sequence of amino acids helix to be dissolved in water
C Nucleic acids
nucleotide 5-carbon sugar phosphate
nitrogen-containing bases adenine cytosine [saıtə¢zi:n]
thymine [¢Өaımi:n] guanine uracil [¢juərəsi:l]
to be strung in long chains deoribonucleic acid
ribonucleic acid to be formed in the chromosomes
to direct the synthesis of proteins
Review
I. Think through the topic of the unit and choose the right answer.
1. Which of the following is not a function of polysaccharides in organisms?
a. energy storage
b. storage of hereditary information
c. formation of cell walls
d. structural support
e. formation of exoskeletons
2. Characteristics of carbon that contribute to its ability to form an immense diversity of organic molecules include its:
a. tendency to form covalent bonds
b. ability to bond with up to four other atoms
c. ability to bond together to form extensive, branched or unbranched carbon skeletons
d. all of the above
3. Foods that are high in fiber are most likely to be derived from
a. plants
b. dairy products
c. meat
d. fish
e. all of the above
4. Proteins differ from one another because
a. the peptide bonds linking amino acids differ from protein to protein
b. the sequence of amino acids in the polypeptide chain differs from protein to protein
c. each protein molecule contains its own unique sequence of sugar molecules
d. the number of nucleotides in each protein varies from molecule to molecule
e. the number of nitrogen atoms in each amino acid differs from the number in all atoms
5. Which, if any, of the following choices does not properly pair an organic compound with one of its building blocks (subunit)?
a. polysaccharides - monosaccharide
b. fat - fatty acid
c. nucleic acid – glycerol
d. protein – amino acid
e. all are paired correctly
6. Which of the following statements about lipids is false?
a. Wax is a lipid.
b. Unsaturated fats are liquid at room temperature.
c. The body does not need any cholesterol.
d. Both male and female sex hormones are steroids.
e. Beef fat is highly saturated.
II. Translate into English (passive constructions are preferable).
1. Дисахариды и полисахариды образуются соединением нескольких моносахаридов в одну цепочку.
2. Дисахариды используются растениями для долгосрочного хранения энергии.
3. Молочный сахар можно определить в крови при помощи биохимических методов.
4. Водоотталкивающие покрытия на листьях и теле некоторых животных образуются благодаря липидам.
5. Практически все химические реакции в клетках проводятся с помощью протеиновых ферментов.
6. Некоторые белки используются организмами как строительный материал.
7. Ты добился всего благодаря деньгам твоего отца.
8. Жизнь клетки невозможно объяснить только химическими принципами.
9. Крахмал можно расщепить на молекулы глюкозы при помощи ферментов.
10. Моносахара объединяются в полимеры при помощи реакции дегидратации.
III. Use the following words and expressions in sentences of your own.
1. to have a short span of life 2. …is found in…
3. to be broken apart 4. commonly
5. to classify into 6. …the reactions that occur…
7. to illustrate by
IV. Read the text and count all prepositional passive structures contained in it.
The Use of Isotopes [¢aısəutəups] in Biology and Medicine
Although all atoms of a particular element have the same number of protons, the number of neutrons may vary. Neutrons do not affect the chemical reactivity of an atom very much, but they do make their presence felt in other ways. First, neutrons add to the atom’s mass, which can be detected by sophisticated instruments such as mass spectrometers. Second, nuclei with “too many” neutrons break apart spontaneously, or decay, often emitting radioactive participles in the process. Those particles can also be detected – for instance, with Geiger [¢gaıgə] counters. The process in which a radioactive isotope spontaneously breads apart is called radioactive decay.
A particularly fascinating and medically important application of radioactive isotopes is positron emission tomography, more commonly know as PET scans. In a common application of PET scans, a subject is given the sugar glucose that has been labeled with (that is, attached to) a harmless radioactive isotope of fluorine. When the nucleus of fluorine decays, it emits two bursts of energy that travel in opposite directions along the same line. Energy detectors are arranged in a ring around the subject. They record the nearly simultaneous arrival of the two energy bursts. A powerful computer then calculates the location within the subject at which the decay must have occurred and generates a map of the frequency of fluorine decays. As the fluorine is attached to glucose molecules, this map reflects the glucose concentration within the subject’s brain. The brain uses prodigious amounts of this sugar for energy; the more active a brain cell is, the more glucose is uses. How can this information be used in biological research?
Let us suppose that a neuroscientist is trying to locate the areas of the brain that are involved in memory. The researcher might give fluorine-labeled glucose to a few volunteer subjects and then ask them to memorize a word list, which is read aloud. Because brain regions that are active during this process would need more energy and would take more fluorine-glucose molecules than they would be taken by inactive regions, the active regions would have more fluorine decays. The PET scans would be taken during the memorization and then pinpoint brain regions active in storing memories of words.
Physicians also use PET scans in the diagnosis of brain disorders. For example, brain regions in which epileptic seizures originate generally have excessively high glucose utilization and show up in PET scans as “hot spots”. Many brain tumors also light up in PET scans. Abnormal metabolism of certain brain regions may also be detected in patients with some mental disorders, such as schizophrenia [skıtsəu¢fri:njə].
V. Compose five questions in Russian relating to the text. In small groups of three practice translating and answering the questions (a curious Russian student asks his/her questions to an American expert in the field, the questions being translated by an interpreter; each student is to perform all three roles).
Listening.
Listen to the text “Protein Structure – a Hairy Subject” and answer the following questions: Which kinds of bonds or bridges between keratin molecules are altered when hair is (a) wet and allowed to dry on curlers; (b) given a permanent wave?
Render in English.
Образование биологических молекул
Живые организмы образуют всевозможные малые органические молекулы, называемые мономерами. Мономеры – это строительные блоки, или субъединицы, более крупных молекул. Они способны соединяться друг с другом, образуя полимеры, известные также под названием макромолекул. Людям давно знакомы такие органические полимеры, как шерсть, шелк, каучук или хлопок; человечество использует их уже не одну тысячу лет. С начала нашего века химики стали изготовлять органические полимеры, пластмассы, соединяя друг с другом различными способами малые органические мономеры, например, диметиловый эфир или этилацетат. Таким образом, возникло искусство или на худой конец ремесло, по сути дела имитирующее природу.
Организм строит свои макромолекулы, соединяя друг с другом мономеры. Процесс этот обратим: полимеры могут быть разрушены до мономеров, из которых они состоят. Именно это, в частности, и происходит в желудочно-кишечном тракте животных: макромолекулы пищи разрушаются здесь до малых молекул, которые затем всасываются в кровь и используются организмом для образования новых макромолекул, принадлежащих уже самому организму. Такое же разрушение, только в гораздо меньшем масштабе, происходит во всех живых клетках: в них также старые молекулы подвергаются расщеплению, а из обломков строятся новые, то есть идет процесс реутилизации.
Все живые организмы содержат четыре главных класса органических соединений: углеводы, липиды, белки и нуклеиновые кислоты. Соединения каждого класса построены из своих особых мономеров, объединяющихся в полимеры.
Unit 3