Exercise 7. Give the English equivalents for the Russian words in brackets.

1. The virus particles are 100 times smaller than (однабактериальнаяклетка). 2. Capsid may contain (ферменты)that enable the virus to enter its (соответствующий) hostcell. 3. Capsid has a symmetrical structure and is built of one or more subunits packed like a (химическийкристалл). 4. Many viruses do not have the envelope and are called (“раздетый” вирус). 5. Some viruses do not kill the cells they infect, but instead (изменятьклеточныефункции). 6. These (защитныемеханизмы) begin with white blood cells, such as lymphocytes, which attack and destroy the virus or the cells it has infected. 7. The genomes of viruses can be comprised of (одноцепочечныеидвуцепочечныедезоксивирусыирибовирусы).

Exercise 8. Translate the following sentences into English.

1. Первый этап репликации вирусов связан с проникновением вирусной нуклеиновой кислоты в клетку организма-хозяина. 2. Нуклеиновая кислота вириона является генетическим материалом вируса (его геномом) и представлена дезоксирибонуклеиновой кислотой (ДНК) или рибонуклеиновой кислотой (РНК), но никогда двумя этими соединениями сразу. 3. При внедрении вируса внутрь клетки-хозяина происходит освобождение молекулы нуклеиновой кислоты от белка. 4. У разных вирусов форма капсида является характерной особенностью (признаком) вириона. 5.Гибель клетки происходит только после выхода из нее вирусных частиц. 6. Бактериофаги играют большую роль в медицине и широко применяются при лечении гнойных заболеваний, вызванных стафилококками.7. У отдельных бактериофагов (вирусов бактерий) смешанный тип симметрии.8. Если специфические («узнающие») рецепторы на поверхности клетки отсутствуют, то клетка не чувствительна к вирусной инфекции: вирус в нее не проникает.

Exercise 9. Test yourself by answering the following questions to see how much you remember and understand.

1. What is a virus?

2. What is the size of a virus?

3. What is the basic structure of a virus?

4. What is the genetic material of a virus?

5. What is the genetic material covered with?

6. What is a nucleocapsid?

7. What is a lipid membrane?

8. Why are the viruses without envelope called naked?

9. Can viruses grow or multiply on their own?

10. How many steps are there in the process of taking over the cell machinery by viruses?

11. What happens to the infected cell?

12. How can viruses be transmitted?

13. What are the body defences against viruses?

14. In what groups can all viruses be divided based on their nucleic acid?

15. What types of arrangement of structural subunits of a capsid do you know?

16. What is a bacteriophage?

 

Exercise 10. Study the chronology of virus discovery.Search the websites to find more information about the scientists who discovered them.

1898 – Loeffler&Frosch – agent of foot-mouth-disease is filterable;

1901 –first human virus, yellow fever virus;

1903 – rabies virus;

1906 – variola virus;

1908 – chicken leukemia virus, poliovirus;

1911 – Rous sarcoma virus;

1915 – bacteriophages;

1933 – influenza virus.

 

Exercise 11. Take the Virus Quiz. Test your knowledge of viruses.

I. Viruses and bacteria are the only infectious agents in plants and animals.

1. True

2. False

II. A virus consists of

1. RNA or DNA and a cell membrane

2. RNA or DNA and a protein coat

3. RNA and DNA and a protein coat

4. Proteins, cell membrane and RNA

III. The size of viruses is usually measured in

1. Centimeters

2. Micrometers

3. Nanometers

4. Millimeters

IV. Viruses require for growth

1. Bacteria

2. Plants

3. Animals

4. Living cells

V. Typically, viruses form … around their nucleic acid.

1. An envelope

2. A cell wall

3. A capsid

4. A capsule

VI. The viral nucleocapsid is the combination of

1. Genome and capsid

2. Envelope and capsid

3. Capsid and spikes

4. Capsomer and genome

VII. Viruses largely lack metabolic machinery of their own to generate energy or to synthesize

1. Protein

2. Carbohydrate

3. Alcohol

4. All of these

VIII. How do viruses reproduce?

1. They divide by mitosis

2. Sexually, by external fertilization

3. Replication outside the host.

4. Inserting DNA into the host cell

IX. What happens after the virus has been taken up by the cell?

1. It begins making protein

2. It divides

3. It inserts into the host DNA

4. It switches to infectious mode

X. The first step in infection of a host bacterial cells by a phage is

1. Adsorption

2. Absorption

3. Penetration

4. Replication