Micro Exam 2c Flashcards
(25 cards)
characterizing a virus
- obligatory intracellular parasites
- contain DNA or RNA
- contain protein coat
- some are enclosed by envelope
- have spikes
- infect only specific types of cells
morphology of virus
- polyhedral (icosahedrons)
- helical
- enveloped
- complex (bacteriophage)
viral species
group of viruses sharing the same genetic information and ecological niche
culturing bacteriophages
form laques on lawn of bacteria
- high specificity
culturing animal and plant viruses
may be grown in cell culture
- newly-isolated cells
- continuous cell lines
newly-isolated cells
grown in medium for only several generations is a primary cell culture
continuous cell lines
may be maintained indefinitely, they are transformed
virus identification
- cytopathic effects
- serological tests
- nucleic acids
lytic cycle
causes lysis and death of cell
- attachment
- penetration
- biosynthesis
- maturation
- release
lysogenic cycle
- prophage DNA incorporated into host DNA
- phage conversion
- specialized or generalized transduction
multiplication of DNA viruses
- virion attaches to host cell
- enters cell and it’s DNA is uncoated
- portion of viral DNA is transcribed, producing mRNA that encodes early viral proteins
- viral DNA is replicated, and some more viral proteins made
- late translation and capsid proteins are synthesized
- virions mature
- virions released
multiplication of + ssRNA
can directly synthesize the proteins required and replicate
multiplication of - ssRNA
- must transcribe a + strand RNA
- + strand RNA serves as template for translation
multiplication of dsRNA
- mRNA created within the capsid and then released into the cytoplasm
host range
refers to spectrum of host cells in which a virus can multiply
- determined by specific attachment site on surface of host cell
what is the capsid composed of?
capsomeres which can be a single type of protein or several types
entry of animal viruses
endocytosis or fusion
exit of animal viruses
budding or rupture in the cell
multiplication of a retrovirus
- RNA is transcribed into DNA by reverse transcriptase
- the viral DNA is then transcribed into the RNA again, but lacks introns this time
- RNA is translated into protein
ocogenic viruses
viruses that are capable of producing tumors
- only RNA viruses that are retroviruses seem to be oncogenic
latent viral infections
viruses remain in asymptomatic host cell for long periods
- cold sores or shingles
persistent viral infection
disease process occurs over a long period of time and are generally fatal
prions
infectious proteins, degenerate brain tissue
- cause CJD and mad cow
entry of plant virus
must enter plant hosts through wounds or with invasive parasites
- can also multiply in insect (vector) cells
