BLS 2020

SOKOINE UNIVERSITY OF AGRICULTURE

COLLEGE OF VETERINARY MEDICINE AND BIOMEDICAL SCIENCES

DEPARTMENT OF MICROBIOLOGY, PARASITOLOGY AND BIOTECHNOLOGY

BLS 108: VIROLOGY UE THEORY

Instructions:

1. Answer ALL questions
2. All questions carry EQUAL weight
3. Diagrams SHOULD be drawn neatly
4. Read each question CAREFULLY before you start attempting

 

QUESTION 1

a) Name any three CELLULAR and three ACELLULAR microorganisms (6 marks)

b) Tabulate any FOUR main differences between bacteria and viruses (8 marks)

c) These two schools of thought about viruses; are those who think viruses are living and those who think viruses are no-living. By providing TWO reasons in EACH case support these two schools of thought (4 marks)

d) Draw a well-labelled structure of an enveloped virus (4 marks) and mention three structural symmetries of viruses (3 marks)

 

QUESTION 2

Differentiate the following terminologies/phrases as they are used in virology (25 marks)

a) A virion from a prion

b) A virus from a provirus

c) A positive (+) strand RNA from a negative (-) strand RNA viral genome

d) A susceptible cell from a permissive cell

e) Virus assembly from virus maturation

 

QUESTION 3

a) Name any FOUR organelles and ONE part of the cell that support the survival of viruses in the host cell (5 marks)

b) Use the diagram below to answer all the questions below it

i) Name steps 1 to 7 and step 10 labelled in the figure above (8 marks)

ii) Explain briefly what is happening in steps 1, 2, 5, 6 and 7 (5 marks)

iii) What is the name of structures presented at number 9? (1 mark)

iv) What is the overall name of what is happening in the figure above? (2 marks)

v) Name ONE virus that can accomplish what is happening in the figure above (1 mark)

vi) Name the enzymes and one function for each enzyme involved in steps 2, 5 and 8 (3 marks)

 

QUESTION 4

a) Explain why antibiotics can not be used for treating viral diseases (3 marks)

b) Most antiviral agents work by inhibiting viral DNA synthesis. Briefly describe the mechanism behind antiviral agents targeting the viral DNA synthesis (4 marks)

c) Mention SIX groups of anti-HIV agents that target different steps in the replication cycle of HIV and provide one example of anti-HIV agents for each group (12 marks)

d) Why is HIV hard to treat? (6 marks)

 

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