Viral infections

Question 1

Inner components of a virus

Answer 1

Inner components

• Viral genome
• (nucleoid): diverse, composed of either RNA or DNA
• Viral enzymes
• required for viral replication within the host cell:
• DNA-dependent RNA
• polymerase
• RNA-dependent RNA
• polymerase
• RNA-dependent DNA polymerase (reverse transcriptase

Question 2

Outer components of a virus

Answer 2

Outer components

*Capsid:
* Single- or double-layer protein shell that
surrounds the nucleoid * Arranged of subunits, known as capsomers
* 3 structural patterns:
* Icosahedral * Helical * Complex

*Envelope:
* May or not be present
* Surrounds nucleocapsid
* Composed of virus-specific proteins
* , lipids
* , and carbohydrates
* (derived from host cell membranes)

Question 3

A susceptible cell…

Answer 3

Has a functional receptor for a given virus - the cell may/may not be able to support viral replication

Question 4

A resistant cell…

Answer 4

Has no receptor - it may/may not be competent to support viral replicationa

Question 5

A permissive cell…

Answer 5

Has the capacity to replicate virus - may/may not be susceptible

Question 6

A susceptible and permissive cell is the only cell that can…

Answer 6

take up a virus particle and replicate it

Question 7

Virion life cycle

Answer 7

1. Inoculation - inoculum of virus binds to cells
2. eclipse - virions penetrate the cell
3. Burst - host cells release many viral particles
4. Burst size - number of virions released per life cycle