MicroBiology- Viruses

Question 1

VIRUS

Answer 1

• Viruses aren’t living organisms→ they are collections of genetic material (RNA or DNA) enclosed in a protein coat (capsid)
• Can’t reproduce like a living cell→ instead invade host cell and hijack reproductive mechanisms

Question 2

VIRUS STRUCTURE

Answer 2

• Genetic material in protein shell
• Some viruses have outer layer formed from plasma membrane of host cell
• In some viruses→ some enzymes they need for reproduction

Question 3

VIRUS REPRODUCTION

Answer 3

• Virus attaches to specific host cell surface
• Virus penetrates host cell→ becomes ‘uncoated” → its genes are released
• Multiple copies of the viral genes are made
• Viral proteins are made using info in viral genes BUT using host cell ribosomes and amino acids
• Multiple copies of the virus are assembled
• New viruses leave the cell to infect other cells→ as they do so they lyse the cell or weaken it so it dies

Question 4

VIRAL INFECTIONS

Answer 4

• Most viral infections are acute; within short periods after infection the immune system eradicates virus
• Some viral infections (e.g. Hepatitis C) are chronic: body never completely removes virus
• Some show latency; prolonged infection period (with viruses slowly reproducing) during which infected person shows no signs or symptoms