Microbiology: Viruses

Question 1

How do viruses differ from bacteria?

Answer 1

Smaller, non-living, no cell wall, need a host cell

Question 2

What are some characteristics of viruses?

Answer 2

• has RNA or DNA
• basic classification based on the presence or lack of outer covering
• core is surrounded by a protein coat called a capsid (all viruses have them)
• some have an envelope, outer layer of lipids and proteins

Question 3

What are the 3 types of viruses?

Answer 3

-Unenveloped
(capsomeres)
-Enveloped virus
-Bacteriophage (infects bacteria)

Question 4

What are the 6 life cycle steps of a virus?

Answer 4

• Adsorption
• Penetration
• Uncoating
• Replication
• Assembly
• Release

Question 5

What is adsorption?

Answer 5

Virus must first adhere/attach to surface of a living cell (must be specific to the receptor)

Question 6

What is penetration?

Answer 6

Virus is taken into the cell

Question 7

What is uncoating?

Answer 7

Capside is removed, release of RNA or DNA, combines its DNA with host cell’s

Question 8

During replication, what are the three other cycles the virus can follow?

Answer 8

• Lytic (make copies of itself until done, then lyse the cell)
• Persistent infection cycle (stays dormant - sounds like lysogenic)
• Host cell transformation (keeps replicating and can cause tumours)

Question 9

What is assembly?

Answer 9

New viruses are assembled

Question 10

What is release?

Answer 10

New viruses lyse the host cell and are released into the body

Question 11

What are the 4 ways antivirals stop the virus’ attack?

Answer 11

• Stop viral attachment
• Inhibit replication
• Inhibit assembly of the virus
• Stop release of the virus from the cell