Introduction to virology Flashcards
Infectious obligate intracellular parasite with genetic material, protein coat, and membrane
virus
viruses can infect all cellular life forms, found in soil, air and water
viruses are ubiquitous
viruses cause disease in
animals
crop plants
industries with bacterial fermentation
uses of bacteria
phage typing
enzyme sources
pesticides
anti bacterial
anti cancer agents
gene vectors
viruses outnumber cellular life by :
10:1
size of viruses
10-300 nm wide
20-800 nm long
nucleic acid of viruses
either dna or rna
(bacteria have both)
is protein present on viruses
yes (as with bacteria)
are viruses cellular
no (bacteria are)
do viruses have cytoplasmic membranes
no (bacteria yes)
are ribosomes present
no (with one exception)
do viruses geow and self replicate
no
do viruses have a metabolism
no
responsiveness of viruses
some phages respond to a host cell by injecting their genomes
also called defective viruses because they have no protein
viroids
genetic material present in viroids
only RNA
has no genetic material but can self tepkicate through PrP proteins causing death in a matter or 3 months
prions
does not induce immune response because it is similar to original protein
prions
smallest viruses that infect bacteria
bacteriophages
largest virus at 970 nm
ebola
size of viruses
ultramicroscopic
why do viruses not fulfil the characteristics of life
-lack of enzyme for metabolic processes
-lack machinery for synthesizing proteins
viruses multiply by
assembly line method
single folded polypeptide chain
subunit
unit from which capsids or nucleocapsids are built
structural unit (protomer, assymetric unit)
morphological unit that arise from interaction of the proteins within the repeated structural units forming capsid
capsomere
protein shell surrounding genome
capsid
host cell derived lipid bilayer
envelope (viral membrane)
protein assembly within particle, used when there is a discrete substructure
nucleocapsid
infectious virus particles
virion
three parts of the viral structure
inner nucleic acid core
capsid
envelope
DNA or RNA
inner nucleic acid core
protein coat surrounding the nucleic acid
capsid
found in some larger viruses
envelope
associate to form the capsid
capsomeres
has symmetric structure
helical – irregularly shaped and spiral
icosahedral – cubical with 20 flat sides
shape of faces of an icosahedral viruses
equilateral triangle
5 at the top
5 at the bottom
10 around the middle
13 vertices
three axes of symmetry
twofold
threefold
twofold
