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?
Reading
I. Put paragraphs of the following abstract in order, then read and translate it.
Energy Carriers in Cells
1 ATP is admirably suited to carry energy within cells. The bonds joining the last two phosphate groups of ATP to the rest of the molecule (sometimes called high-energy bonds) require a large amount of energy to form, so considerable energy can be trapped from exergonic reactions; it readily releases its energy in the presence of appropriate enzymes. Under most circumstances, only the bond joining the last phosphate group (the one joining phosphate to ADP to form ATP) carries energy from exergonic to endergonic reactions.
2 Energy can also be transported within a cell by other carrier molecules. In some exergonic reactions, including both glucose metabolism and the light-capturing stage of photosynthesis, some energy is transferred to electrons. These energetic electrons (in some cases, along with hydrogen atoms) are captured by electron carriers.
3 The life span of an ATP molecule is very short, because this energy carrier is continuously formed, broken apart to ADP, and resynthesized. More stable molecules, such as sucrose, glycogen, starch, or fat, store energy in our body for hours, days, or months.
4 Common electron carriers include nicotinamide adenine dinucleotide and its relative flavin adenine dinucleotide. Electron-carrier molecules pick up electrons generated by exergonic reactions and hold them in high-energy outer electron shells. Hydrogen atoms are often picked up simultaneously. The electron is then deposited with another molecule to drive an endergonic reaction, typically the synthesis of ATP.
5 The most common energy-carrier molecule in cells is adenosine triphosphate, or ATP. It is a nucleotide composed of the nitrogen-containing base adenine, the sugar ribose, and three phosphate groups. Energy released in cells through glucose breakdown is used to drive the synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate. ATP carries this energy to sites in the cell that perform energy-requiring reactions, such as the synthesis of proteins or muscle contraction. The ATP is then broken down to form ADP and inorganic phosphate. During these energy transfers, heat is given off at each stage, and there is a loss of usable energy.
II. Choose the right answer:
ATP is important in cells because:
a. it is assembled into long chains that make up cells membranes.
b. it acts as an enzyme.
c. it accelerates diffusion.
d. it transfers energy from exergonic reactions to endergonic reactions.
e. all of the above.
III. Fill in the blanks with appropriate terms from the text:
1. Some substances in our organism are formed just for seconds, broken apart and then ………….. .
2. If a substance contains no carbon molecules, it is an ………………….. substance.
3. ……………………….. is among common electron carriers.
4. The synthesis of proteins is an …………………… reaction.
5. During exergonic reactions heat is …………………….. .
IV. Using italicized words compose three true sentences and two false ones. Swap the sentences with your partner and try to guess true and false ones.
Language focus 1
Ved Forms. Participle Constructions
1 Verb forms like left, studied, broken, finished are called ‘past participles’, or Ved Forms. Ved Forms can be used with auxiliary verbs be and have to make perfect and passive verb forms.
I’ve completed the work. We’ll be sent for when it’s necessary.
2 Past participles can be used like adjectives.
He’s got a broken heart.
3 Participles can combine with other words into clause-like structures.
Most of the students invited to the party didn’t turn up.
Accepted by all the scientists, the new idea became a breakthrough concept.
4 Ved Forms are often used after nouns in order to define or identify the nouns.
We couldn’t agree on any of the issues discussed. (= … the issues that were discussed.) (NOT … the discussed issues.)
The students questioned gave very different opinions. (= The people who were questioned…) (NOT The questioned students…)
We had the only sample left. (NOT … the only left sample.)
5 A few participles change their meaning according to their position. Compare:
- a concerned expression (= a worried expression)
the people concerned (= the people who are/were affected)
- an involved explanation (= a complicated explanation)
the people involved (= the people concerned)
- an adopted child (= a child who is brought up by people who are not his/her biological parents)
the solution adopted (= the solution that is/was chosen)
I. Find Ved Forms in the following sentences and say what role they play in the sentence.
1. Sugar, produced in photosynthetic organisms, contains far more energy than do the carbon dioxide and water from which it is formed.
2. Many of chemical reactions in a cell are linked in sequences called metabolic pathways.
3. The original reactant molecule undergoes a series of reactions, each catalyzed by a specific enzyme.
4. Under the influence of certain type of poisons the active site of an enzyme remains plugged up, so no substrate molecule can enter.
5. Nuclear reactions in the sun produce concentrated energy (sunlight) along with vast increases in entropy.
6. Living organisms constantly use the energy given off by exergonic reactions to drive essential endergonic reactions, as shown in Figure 4-4b.
7. The energy stored is used later in various life processes.
II. Say whether the information contained in the participle constructions is necessary to the meaning of the sentence, or it can be omitted.
1. Energy released in cells through glucose breakdown is used to drive the synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate.
2. Each enzyme has a dimple or groove, called the active site, into which reactant molecules, called substrates, can enter.
3. Muscle movement is an endergonic reaction coupled to the exergonic reaction of ATP breakdown.
4. Some enzymes also require the presence of other molecules called coenzymes, typically derived from water-soluble vitamins, in order to function.
5. Far lower temperatures than those required to fry an egg can still be too hot for normal enzyme function.
Now formulate the rule for putting commas. Do we need commas when the information contained in the participle construction can be omitted?
III. Compose your own sentences using the participle constructions given below. Pay attention to the punctuation!
1. … directed by enzymes … 2. …, not usually spoken of, …
3. … kept in secret … 4. … believed to be true by many …
5. …, meant to draw our attention to the idea of Justice, …
Language focus 2
Absolute Participle Construction
A participle construction can have its own subject. This happens often in a rather formal style, for example, in scientific texts:
The active site changed, the reaction continues.
The subject is often introduced by with. It can have different meanings:
time (when?); cause (why?); circumstances (how?); place (where?).
I. Translate the following sentences into Russian paying attention to the function of the participle construction.
1. The breakdown or synthesis of a molecule within a cell normally occurs in many discrete steps, each catalyzed by a different enzyme.
2. Most enzymes function optimally at a pH between 6 and 8, the level found in most body fluids and maintained within cells.
3. With the process initiated, the reaction lasts until the needed quantity of the substance is achieved.
4. The active site plugged up, the substrate molecules cannot enter and the reaction is stopped.
5. The energy released as heat, the amount of entropy increases.
II. Think of your own phrases with absolute participle construction using words:
… found … … broken … … closed …
… rejected … … catalyzed …
Language focus 3
Participles of Durative and Terminative Verbs
In English one can find verbs of terminative and non-terminative (durative) lexical character.
Terminative verbs denote an action implying a certain limit beyond which it cannot go: to come, to bring, to build, to give, to take, to receive, to find, to fall, to kill, to die, to become, to stand up, to sit down, to come to.
Durative verbs denote a certain action which does not imply any limit: to live, to exist, to sleep, to love, to be, to have, to possess, to work, to speak, to respect, to hope, to sit, etc.
I. Match the participle with its translation. Pay attention to whether the action expressed has reached a point after which it can no longer continue. Some verbs can have both durable and terminative meanings.
shown освобождаемый, освобожденный
liberated называемый
oxygen-starved разбитый
called выпускаемый, выпущенный
derived (from) испытывающий нехватку кислорода
broken показываемый, показанный
released произошедший, полученный (из)
II. Say whether the participles in the following sentences have a durative or a terminative meaning. Translate the sentences.
A. Potential energy, or stored energy, includes chemical energy stored in the bonds that hold atoms together in molecules, electrical energy stored in a battery, and positional energy stored in a diver poised to jump.
B. A chemical reaction converts one set of substances, called the reactants, into another set, the
products.
С. In most cases, an enzyme catalyzes a single reaction that involves one or two specific molecules but leaves even quite similar molecules untouched.
D. Enzymes are biological catalysts, normally proteins synthesized by living organisms.
E. Temperature also affects the rate of enzyme-catalyzed reactions.
Words, Words, Words
I. Look through the sentences in the exercises of this unit. Make a classification of new words and phrases according to any parameter chosen by you.
II. Write an abstract describing the flow of energy in the Earth’s living systems and the functioning of enzymes.
Render in English.
Большая часть химических реакций, протекающих в организме, регулируется ферментами, то есть белковыми молекулами, выполняющими функцию катализаторов. Катализатором называют вещество, ускоряющее химическую реакцию, которая без него протекает медленно. Сам катализатор во время этой реакции стойких изменений не претерпевает.
Каждый из ферментов катализирует только те реакции, в которых участвуют молекулы только какого-нибудь одного или нескольких видов. Причина этого в том, что ферменты связываются со своими субстратами, т. е. теми веществами, на которые они действуют. У фермента имеется активный центр. Форма и химическое строение этого активного центра таковы, что с ним могут связываться только определенные субстраты. Катализируя реакцию, фермент тесно сближает молекулы своих субстратов, так что те части молекул, которым предстоит прореагировать, оказываются друг подле друга. Субстрат, присоединившись к ферменту, несколько изменяется. Фермент может, например, притягивать электроны, вследствие чего в некоторых связях молекулы субстрата будет возникать напряжение. Это, в свою очередь, может повышать реакционную способность молекулы.
Предполагается, что именно таким путем фермент и ускоряет реакцию. Активность ферментов находится в зависимости от температуры и кислотности (acidity), а также от концентрации молекул субстрата, самих ферментов и коферментов (витаминов и других веществ).
Unit 4
Principles of Evolution
Introduction
I. Listen to a brief biography of a very famous scientist. The student first to say the scientist’s name will win the contest.
II. In pairs fill in the gaps.
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collecting new specimens, scrutinizing their structures, and
categorizing them.
b) In 1831, when Darwin was only 22 years old, the British
government sent Her Majesty’s Ship “Beagle” on a 5-year
surveying expedition that ……….. first ………… the coastline of South America and then ………….. the world.
c) In South America he discovered a snake with rudimentary hind limbs, calling it
“the passage by which Nature ……… the lizards to the snakes”.
d) But constantly gnawing on his mind was the problem of the ………….. of species.
III. Make up a story of Darwin’s work, including the following words:
tortoise (черепаха) prickly pear cacti (опунции) finch (вьюрок) beak (клюв) Galapagos Islands isolated on separate islands “On the Origin of Species”, 1859
Reading
I. Read the following extract about fossils. There are several sentences taken out of the text. Put them into correct places.
a. Fossil remains also showed a remarkable progression of form.
b. These fossils (from Latin, meaning “dug up”) resembled parts or living organisms.
c. In fact, any tangible trace of an organism that is preserved in rock or sediments is a fossil.
d. The rapidly accumulating fossil discoveries also revealed that fossils come in many forms.
| As new lands were explored, excavations for roads, mines, and canals revealed that many rocks occur in layers. In some cases, a few strangely shaped rocks or fragments were found embedded within one of these layers. ( ) At first, fossils were thought to be ordinary rocks that wind, water or people had worked into lifelike forms. As more and more fossils were discovered, however, it became obvious that they were in fact the remains of plants or animals that had died long ago and been changed into or in some ways preserved in rock. ( ) The classic image of a fossil is of bones or other hard parts (such as shells) that have been transformed into rock by aeons of geological processing. But fossils also include casts, molds, and other impressions that organisms left in ancient sediments before decomposing. Some of the most interesting and informative fossils are the trails, burrows, tracks, or droppings that organisms left behind. ( ) These windows into the past are fascinating in and of themselves, but the distribution of fossils in rock can also be revealing. After studying fossils carefully, the British surveyor William Smith (1769-1839) realized that certain fossils were always found in the same layers of rock. Further, the organization of fossils and rock layers was consistent: Fossil type A could always be found in a rock layer resting atop an older layer containing fossil type B, which in turn rested atop a still older layer containing fossil type C, and so on. ( ) Most fossils found in the lowest (and therefore oldest) rock layers were very different from modern forms; the resemblance to modern forms gradually increased upward toward younger rocks, as if there were indeed a ladder of Nature stretching back in time. Many of these fossils were the remains of plant and animal species that had gone extinct – that is, no members of the species still lived on Earth. Putting these facts together, scientists came to the inescapable conclusion that different types of organisms had lived at various times in the past. |
II. Find in the text words meaning:
showed ……………………
fixed firml ……………………
unchanged ……………………
ages ……………………
objects formed by molding ……………………
feces ……………………
similarity ……………………
no longer existing ……………………
III. Which of the following are fossils?
a. pollen grains buried in the bottom of a peat bog
b. the petrified cast of a clam’s burrow
c. the impression a clam shell made in mud, preserved in mudstone
d. an insect leg sealed in plant resin
e. all of the above
Language Focus 1
Ving Forms: Use, Terminology and Types
1 We can use Ving Forms (e.g. smoking, walking) not only as verbs, but also like adjectives, adverbs or nouns. Compare:
You’re smoking too much these days. (part of a verb in present continuous)
There was a smoking cigarette end in the ashtray. (adjective describing cigarette end)
She walked out of the room smoking. (similar to an adverb)
Smoking is bad for you. (noun: subject of sentence)
2 When Ving Forms are used as parts of verb forms, or like adjectives, they are called ‘present participles’. (This, as well as ‘past participle’, is not a very suitable name, because both forms can refer to the past, present or future.) When they are used more like nouns, they are often called ‘gerunds’.
3 Ving Forms can be combined with other words to form clause-like structures.
She went running out of the room.
Collecting stamps was a hobby of his.
Having lost all my money, I went home.
I. Find in the Reading Text examples of various uses of Ving Forms and name them.
II. Fill in the table:
| Present | Perfect |
| (not) preserving (not) being preserved | (not ) having ……………… (not) ………… been preserved |
III. Choose the correct form of those given in the brackets:
1 (Having spent/Spending) all his money, he went to borrow some from his sister.
2 (Having preserved/Having been preserved) by the efforts of two governments, the reserve is now in a very good condition.
3 (Not seeing/Not being seen) her often was harder than I had thought.
4 The gulls, though (watching/being watched) all the time, did not pay attention to the intruders.
5 For those (trying/having tried) to produce a good impression I would like to note that I do not look at the appearance of students.
6 (Not knowing/Not having known) the facts, we cannot do anything.
7 Although (having listened to/being listened to) I felt ignored.
8 I am afraid that even (having been done/having done) everything I will fail to answer his questions.
Ving Forms Used as Modifiers
Ving Forms can be used before nouns. This can happen both with noun-like Ving Forms (‘gerunds’) and adjective-like Ving Forms (‘participles’). The two structures do not have quite the same kind of meaning. Compare:
a waiting room (= a room for waiting – waiting is a gerund, used rather like a noun)
a waiting train (= a train that is waiting – waiting is a participle, used rather like an adjective)
IV. Place Ving Forms into two groups: gerunds and participles. Note the stressed word with a blob.
a sleeping pill
working conditions
working men and women
writing board
a sleeping child
a living room
living things
cutting edge
a listening exercise
listening students
Language Focus 2
Determiners, possessives and object pronouns before Ving Forms
1 We can often use determiners (for example, the, my, this) with noun-like Ving Forms.
the opening of Parliament I don’t mind your going without me.
Does my smoking annoy you? I hate all thisuseless arguing.
John’s going to sleep during the wedding was rather embarrassing.
She was angry at Lina’s trying to lie to her.
2 Note that possessives and pronouns are not used before Ving Forms if it is already clear who is being talked about.
Thank you for waiting. (NOT Thank you for your waiting.).
No is often used with Ving Form to say that something is not allowed, or is impossible. The structure often occurs alone in notices; it can also follow there is.
No smoking No parking
Sorry – there’s no smoking in the waiting room.
3 In an informal style it is more common to use object forms (like me, John) instead of possessives (my, John’s) with Ving Forms, especially when these come after a verb or preposition.
I don’t mind you going without me.
She was angry at Lina trying to lie to her.
Some verbs (e.g. hear, watch, feel) are normally followed by an object+Ving Form.
I saw him getting out of the car. (Not I saw his getting…)
I. Put the words into right order to make sentences.
1. hate / I / saying / his / words / to / such / my daughter.
2. you / seen / dancing / him / have?
3. made /up / She / mind / ‘s / her / -/ is / arguing / there / no / with her.
4. always / laughing / are / making / my / mistakes / at / you.
5. for / thank / so / being / you / kind.
6. ever / do / playing / you / the / enjoy / him / violin?
7. upset / the / boys / I / behaving / was / badly / so / by
II. Translate from Russian into English.
1. Я видел, как ты разговаривала с этим человеком.
2. Он шел домой, весело напевая.
3. Этот человек заслуживает, чтобы его выслушали.
4. Развитие разнообразных умений и способностей – наша задача.
5. Посмотри на того человека, который стоит отдельно от остальных.
6. Говорящий лист: так индейцы называли письмо по бумаге.
7. Обожаю кататься на лошади!
Words, Words, Words
I. In 1858, Charles Darwin and Alfred Wallace independently described a mechanism for evolution in remarkably similar papers that were presented to the Linnaean Society in London. They stated that the evolutionary theory arises from scientific observations and conclusions based on them. But how did Darwin and Wallace arrive at the conclusion that life’s huge variety of excellent designs arose by a process of descent with modification? The chain of logic leading to this powerful conclusion turns out to be surprisingly
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summarized below in modern terms. However,
the observations and conclusions are not given in
the right order. Your task is to match the observations
and conclusions and to place them properly.
Observation 1: Natural populations of all organisms have the potential to increase rapidly, because organisms can produce far more offspring than are required merely to replace the parents. (A population consists of all the individuals of one species in a particular area.). Nevertheless, the sizes of most natural populations and the resources available to maintain them(such as food and appropriate habitat) remain relatively constant at the time.
Conclusion …: Over many generations, differential, or unequal, reproduction among individuals with different genetic makeup changes the overall genetic composition of the population. This process is evolution by natural selection.
Conclusion …: Therefore, there is competition for survival and reproduction. In each generation, many individuals must die young, failto reproduce, produce few offspring, or produce less-fit offspring that fail to survive and reproduce in their turn.
Conclusion …: The most well-adapted (the “fittest”) individuals in one generation tend to be the ones that leave the most offspring. This is natural selection, the process by which the environment selects for those individuals whose traits best adapt them to that particular environment.
Observation …: Individual members of a population differ from one another in their ability to obtain resources, withstand environmental extremes, escape predators, and so on.
Observation …: At least some of the variation among individuals in traits that affect survival or reproduction is due to genetic differences that may be passed on from parent to offspring.
II. Use the words in bold given in I to describe the evolution of the horse, Equus. See the picture below:
Language focus 3
Ving Forms after Verbs
After some verbs we can use Ving Form, but not normally an infinitive:
I enjoy traveling. (NOT I enjoy to travel.)
He’s finishedrepairing the car.(NOT He’s finished to repair…)
The doctor suggested takinga long holiday. (NOT The doctor suggested to take…)
Some common verbs that are followed by Ving Form:
admit detest feel like leave off resist
appreciate dislike finish mention risk
avoid endure forgive mind (can’t) stand
burst out enjoy give up miss suggest
consider escape (can’t) help postpone understand
contemplate excuse imagine practice
delay face involve put off
deny fancy keep (on) resent
I. Match parts of the sentences and write out the verbs that require Ving Form after them. More than one variant is possible.
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The accused denied being treated in such a way.
We dislike his getting so much money for nothing.
Do you feel like going out tonight?
Do you fancy stealing the money because I was
in a different place at that time.
Do you mind my closing the window? There is a draught.
I strongly resent being guilty until his execution.
He can’t stand playing some old tune?
II. Compose dialogues including at least four of the following expressions.
face losing one’s job mention one’s behaving badly consider doing everything at once give up drinking avoid speaking about it in public
keep (on) smiling suggest choosing another candidate understand one’s complaining
Some of the verbs listed above and some other can be followed by object + Ving Form.
I dislike people telling me what to do.
I can’t imagine him working in a laboratory.
III. Compose sentences using the given words:
suggest + (he) + visiting
can’t stand + (I) + playing
fancy + (they) + going
resent + (she) + complaining
not admit + (we) + saying
consider + (the matter) + developing
not avoid + (mum) + talking
understand + (the professor) + falling asleep
not mind + (I) + leaving
dislike + (they) + looking
prevent + (he) + from finding out
not stop + (the judge) + from having revenge on
IV. Translate into English.
1. Дарвин любил наблюдать за животными и растениями, собирать образцы и классифицировать их.
2. Проблема происхождения видов до сих пор требует глубокого исследования.
3. Поскольку камень встречается в пластах, по возрасту пласта можно установить возраст ископаемого, сохранившегося в этом камне.
4. Века геологической обработки сформировали удивительные образцы давно вымерших фауны и флоры древнейших времен.
5. Ископаемые остатки раскрывают перед нами лестницу природы, простирающуюся вглубь веков.
6. Зерна пыльцы, захороненные в торфе, не являются ископаемыми, так же как не являются ими насекомые, сохранившиеся в окаменевшей древесной смоле.
7. Проведя некоторое время на Галапагосских островах, Дарвин пришел к важным выводам, касающимся эволюции организмов путем естественного отбора.
8. Эволюция путем естественного отбора предполагает выживание потомства наиболее приспособленных к среде обитания особей каждого поколения.
9. Оставив наиболее многочисленное потомство, наиболее приспособленные особи изменяют общий генетический состав естественной популяции.
10. Полученный от родителей новый набор генов, способствующих лучшему выживанию, начинает преобладать в популяции.
Retell in English.
Основные принципы эволюционного учения Ч. Дарвина сводятся к следующим положениям:
1. Каждый вид способен к неограниченному размножению.
2. Ограниченность жизненных ресурсов препятствует реализации потенциальной возможности беспредельного размножения. Большая часть особей гибнет в борьбе за существование и не оставляет потомства.
3. Гибель или успех в борьбе за существование носят избирательный характер. Организмы одного вида отличаются друг от друга совокупностью признаков. В природе преимущественно выживают и оставляют потомство те особи, которые имеют наиболее удачное для данных условий сочетание признаков, то есть лучше приспособлены. Избирательное выживание и размножение наиболее приспособленных организмов Ч. Дарвин назвал естественным отбором.
4. Под действием естественного отбора находящиеся в разных условиях группы особей одного вида из поколение в поколение накапливают различные приспособительные признаки. Они приобретают настолько существенные отличия, что превращаются в новые виды (принцип расхождения признаков).
Unit 5