Virus Structure and Classification Flashcards
Give the definition of a virus in 4 words or less.
A capsid-encoding organism
Which are “filterable agents”: bacteria or viruses?
Viruses, because they can pass through a 220nm-pores filter
What does it mean that viruses are “obligate intracellular parasites”?
They can only replicate inside cells
What is the difference between a virion and a virus?
A virus is the whole organism, with all its proteins and replicative abilities, that takes over a host cell. A virion is just the viral genome and capsid.
Name the 3 basic gene modules shared by all viruses.
The viral genome codes for: capsid, replicon, and host cell interacting factors
Which viral proteins are structural and which are non-structural? What does this mean?
Capsid proteins are structural and host cell interacting factors are non-structural, meaning that capsids are always part of the virion while host interacting factors never are.
(Replicon genes may be either structural or non-structural)
How is the shape of a virus’s capsid related to its genome type?
They are not related. Capsid shape and genome type are independent.
What structure characterizes an enveloped virion vs. a naked virion? How does the enveloped virion obtain this structure?
An enveloped virion has a lipid bilayer which it takes from the host cell’s membrane or organelle membranes
List the 3 factors on which virus classification is based.
Host cell, genome type, and virion structure
What is a virus’s nucleocapsid?
Just means the capsid or core
Give 2 terms that refer to the jelly-like layer of proteins that surrounds the capsid in some viruses.
Tegument or matrix
Give the capsid shape, genome type, and enveloped/naked status for adenovirus.
Icosahedral, dsDNA, naked
Give the capsid shape, genome type, and enveloped/naked status for poxvirus.
Complex, dsDNA (with sealed ends), enveloped
Give the capsid shape, genome type, and enveloped/naked status for influenza virus.
Helical, segmented (-) RNA, enveloped
Give the capsid shape, genome type, and enveloped/naked status for HIV retrovirus.
Icosahedral, (+) ssRNA, enveloped
Give the capsid shape, genome type, and enveloped/naked status for herpesvirus.
Icosahedral, dsDNA, enveloped
List in order from smallest to largest: ribosome, bacterium, naked virion, nucleus
Ribosome - Virion - Bacterium - Nucleus
Which of the example viruses is naked: adenovirus, poxvirus, influenza, retrovirus, and herpesvirus.
Only adenovirus is not enveloped
Which of the example viruses have double-stranded DNA: adenovirus, poxvirus, influenza, retrovirus, and herpesvirus.
Adenovirus, poxvirus, and herpesvirus
Which of the example viruses are helical: adenovirus, poxvirus, influenza, retrovirus, and herpesvirus.
Influenza virus
State the 3 unifying principles of virology.
- The genome encodes a capsid.
- The virus infects a cell, survives, replicates, and assembles virions.
- The virion is transmitted to a new host.
