Lecture 9/10: Viruses Flashcards
what is a virus?
genetic element encapsulated in a protein shell
what is a capsid?
protein shell
why are viruses not considered living?
does not have independent metabolism
T or F: viruses do not need a host to carry out energy & protein synthesis
false, they use phages
what is a virion?
extracellular form of a virus
what is the structure of a virus?
- contains DNA or RNA
- has 1 or more fragments
what is a naked virus?
has no membrane around it
what symmetry is rod shape?
helical
what symmetry is spherical shape?
icosahedral
what is the length & width of a helical virus dependent on?
length- nucleic acid strand length
width- size & packaging of capsomeres
what is an example of a helical virus?
TMV
what is icosahedral symmetry?
20 triangular faces + 12 vertices (corners)
what symmetry is the most simple/effective?
icosahedral
where does the phospholipid bilayer in envelope viruses come from?
the host
what are fibrils?
peptidoglycan-like polymer on amoeba viruses
where is the protein found on spike viruses?
surface
what is the function of spike proteins?
attach & enter host cells
what is bacteriophage?
lysozome-like enzyme
what are RNA viruses?
RNA replicase (mRNA->mRNA)
what are retroviruses?
reverse transcriptase (RNA->DNA)
what type of genetic material are viruses missing?
mRNA
why do viruses have fast evoltuion?
due to high error rate
Species name vs Viral name: Italics/not in italics?
species- italics
viral name- not in italics
what is the Baltimore classification?
classifies viruses by nucleic acid type & replication
