6. Viruses Flashcards
What is a benefit for a virus with RNA rather than one with DNA?
RNA is less stable so it can develop and mutate more quickly than DNA.
What is the difference between enveloped and naked viruses and which is easier to destroy?
Enveloped viruses contain lipid but naked viruses don’t. Naked viruses are harder to destroy.
How do the growth curves of bacteria and viruses differ?
Bacteria growth curves are more constant whereas viruses don’t reproduce much for a while and the suddenly exponentially reproduce.
What are the different structures of DNA and RNA found in virsuses?
Double stranded or single stranded. Liner, circular or nicked. Unsegmented or segmented.
What is the difference between plus and minus SS RNA?
+ RNA - genomic RNA can serve as mRNA and be directing translated into protein.
- RNA - genomic RNA cannot serve as mRNA and cannot be translated directly into protein.
How is specific diagnosis of most viral infections obtained?
Molecular detection of their genomes.
What is the viral capsid?
Protein outer coat. Composed of individual subunits, capsomers.
What are the functions of the capsid of viruses?
To protect the delicate inner nucleic acid from harsh environmental conditions. Also may be involved in attachment to host cells.
What are the two basic capsid structures?
Icosahedral and helical.
What is needed for a virus to infect the host cell?
The cell has to have receptors for the virus ligand to bind to for initiation of an infection.
What is needed for a virus to replicate in the host cell?
Cellular machinery.
What is the most commonly used way of classifying viruses?
The Baltimore scheme. It considers the ways viruses inflect.
In medical virology, what is used to classify viruses?
The nucleic acid type and envelope.
What are two categories of effects of a virus on the host cell?
Death of the cell, normally from release of the virus. Cytopathic effects, inclusion bodies on the site of active virus synthesis, or syncytia formation on giant, multinucleated cells by the fusion of plasma membranes, chromosomal damage or inhibition of host cell protein.
What is a common way that viruses cause cancer?
By inactivating tumour-suppressor proteins.
