V. Think of possible questions for the following answers

1. Because viruses are not free-living organisms.

2. It’s the extracellular form of a virus;

3. These organisms are called viroids.

4. Because they do not have ribosomes.

5. The virus derives it from the host cell.

6. It performs three basic functions.

7. The reason is in the frequent changes of the viral DNA or RNA sequences.

8. Viruses can reproduce only in host cells.

9. Such viruses do not destroy the cell at once.

10. Short term diseases are referred to as acute and long-term diseases are called chronic.

VI. Say whether the following statements are true or false according to the text “Viruses”

1. Viruses lack some functions characteristics of other living organisms.

2. All viruses have RNA molecules.

3. At different stages of their development virions can transform into viroids or prions.

4. The parasitic nature of viruses is manifested in their dependence on host cells for energy and protein synthesis mechanism.

5. A virus deprived of its capsule can never penetrate into the host cell.

6. The virion capsid performs a protective function.

7. The main criteria used for viruses classification are their size and shape.

8. Viruses lack the mechanism of correcting the errors in the nucleic acid sequences.

9. The viruses are harmless for their host cell as long as the latter are not subjected to specific physical or chemical influences.

10. Medicine of the future may rely on viruses for the repair of certain genetic defects in humans.

VII. Skim the text “Viruses” one more time to find the words with the following meanings

to a large extent or degree;

to pass into or through;

the inner part of a thing: inside;

the amount of specified material contained; proportion;

a natural enclosing covering;

to take something that belongs to someone else forcibly;

marked by moderation; not extreme or excessive; mild;

hurt or damage;

affected in a negative way and suffering as a result of it;

occurring again after an interval.

VIII. Use the words from the previous exercise to fill in the blanks in the sentences below

1. Most viruses enclosed in ________ appear to be spherical, although the rhabdoviruses are elongated cylinders

2. The weather here continues to be ________!

3. Even after all these years, the patient still suffers from constantly ________ respiratory problems and skin rashes.

4. Elderly people are frequently ________ by this type of pneumonia.

5. The sea turtle's natural habitat has been ________ reduced.

6. Beckham has missed several games through ________.

7. Aiming your light down into it, you can see right through the membrane to the cell ________.

8. Science has ________the mysteries of nature.

9. Two hijackers used fake explosives to ________ the airliner.

10. The fat ________ of this cheese is 60%.

11. With trembling hands Mr Utterson opened the ________.

12. People pay as much attention to your voice as to the ________ of your speech.

13. If this bacterium gets into the body by means of an ________ or wound, the bacterial capsule stimulates the body to wall off the bacteria into an abscess, which reduces the spread of the bacteria but also makes them much more difficult to eradicate.

14. Bromocriptine increases the level of dopamine in the brain, which controls rhythmic biological cycles ________ every 24 hours.

15. The sun's rays can ________ the sea to a depth of twenty metres.

16. Heat is trapped in the Earth's ________.

FOCUS ON GRAMMAR

I. Read the following sentences paying special attention to the highlighted phrasal verbs. What do they mean? What do you know about phrasal verbs?

a) Viruses cannot reproduce and carry on metabolic processes without a hostcell.

b) Some viruses cause acute disease from which there is fairly rapid recovery but may persist in the tissues, remaining dormant for long periods of time, and then become active again, bringing about serious disease decades later.

c) Powerful digestive enzymes concentrated in the lysosome break down worn-out organelles and ship their building blocks to the cytoplasm where they are used to construct new organelles.

II. Match each of the following phrasal verbs to the correct meaning

break down bring up bring back draw on give off go on make up set off turn out work out

a) to make use of something; b) to make something start happening; c) to separate (as a chemical compound) into simpler substances: decompose; d) to develop; e) to happen; f) to mention; to introduce a subject; g) to happen in a particular way; to have a particular result; h) to compose; i) to produce a smell, light, heat, a sound, etc.; j) to reintroduce.

III. Use a proper phrasal verb from the previous exercise to complete each of the following sentences

1. Molecular biology, which studies the chemical structures and processes of biological phenomena at the molecular level, __________ several disciplines and has become one of the most important biological sciences.

2. Biochemists have probed the biological interactions of the organic molecules that __________ life on our planet.

3. Organisms such as fungi and bacteria __________ dead or dying matter into nutrients that can be used again.

4. A French naturalist Georges Cuvier utilized large collections of biological specimens sent to him from all over the world to __________ a systematic organization of the animal kingdom.

5. A valuable method useful in tracing the movement of substances in living matter is radioautography: when radioactive nutrients, which can be incorporated into cells, are injected into animals, they __________ detectable rays by which their presence and location can be determined.

6. The formation of the cell theory — all plants and animals are made up of cells — marked a great conceptual advance in biology, and it resulted in renewed attention to the living processes that __________ in cells.

7. Avicenna was an outstanding Persian scientist around the beginning of the 11th century. He was the true successor to Aristotle. His writings on medicine and drugs did much to __________ the works of Aristotle __________ to Europe, where they were translated into Latin from Arabic.

8. Most mutations, however, __________ to be deleterious and often lead to some impairment or to death of the organism.

9. The life cycle of slime molds, or humans, or any other multicellular organism, __________ a fundamental and still largely unsolved problem.

10. Protein molecules range from the long, insoluble fibers that make up connective tissue and hair to the compact, soluble globules that can pass through cell membranes and __________ metabolic reactions.

LISTENING COMPREHENSION

I. You are going to hear a text about the well-known disease cholera and the agent causing it. Before listening discuss the meaning of the words in the box below with your classmates or teacher

cramps vomiting watery diarrhea to deplete mild symptoms lethal infection genetic stowaway immune response

circulatory shock to devastate to contaminate water supply to harbor a viral infection bacteriophage to acquire virulence to set on the right track

small intestine chloride ions sodium ions to leak out life-threatening to bear a gene route to reveal

II. Listen to the first fragment of the text and tick the items below that are mentioned in it

· Symptoms of the disease;

· Statistics on the number of people suffering from cholera worldwide;

· Regions covered by epidemics of the disease;

· The pathogene;

· The course of infection;

· Development of cholera vaccines;

· Prevention of the disease.

III. Listen again and note down as much information on the items you’ve ticked as possible

IV. Listen to the second part of the text and choose all possible continuations for the sentences below

2. Cholera vaccines have never worked well …

a) because there are many strains of the bacterium;

b) because Vibrio Cholerae is not the pathogene itself;

c) because of frequent genetic mutations in the pathogene.

3. A vaccine is …

a) a mutated pathogene; b) a disabled virus; c) a weak pathogene.

4. Using electron microscope researchers have found …

a) a gene responsible for the production of cholera toxin;

b) a phage inserted into the bacterial cell;

c) that some bacteria Vibrio Cholerae lack pili.

5. The phage penetrates into Vibrio Cholerae …

a) trough pili;

b) across the plasma membrane;

c) by pricking the cell wall.

6. Bacterial cell without pili …

a) can never cause cholera in humans;

b) usually cause the disease;

c) do not produce cholera toxin.

 

 

WRITING