Ch 13 virus Flashcards
define a virus
obligatory intracellular parasite
contain either DNA or RNA (not both)
no ribosomes or ATP generation
have a protein coat
enveloped virus
phospholipid membrane around nucleic acid
complex virus
head sheath and tails
injects nucleic acid into cell
scientific naming of virus
family name ends in -viridae
gnus name ends in -virus
viral species
a group of viruses sharing the same genetic info and host
How do you culture a virus
must be grown in living cells
animal virus grown in living animals, embryonic eggs, and cell cultures
obligatory intracellular parasite
has to be grown in a host
3 techniques used to identify viruses
- cytopathic effects (change in cell appearance
- serological tests (antibodies)
- Nucleic acids
Lytic cycle- 5 step
- attachment
- penetration
- biosynthesis
- maturation
- release
Lysogenic cycle -3 step
- prophage DNA incorporated into host DNA
- phage conversion
- specialized transduction
one-step growth curve
- attachment
- eclipse- no detectable virus
- maturation
- release-> acute infection
retrovirus
have RNA with reverse transcriptase to make viral DNA
+ sense RNA
is mRNA and can begin replication immediately in the cytoplasm
- sense RNA
need to be turned into + sense RNA first
animal virus replication
- attachment
- penetration
- uncoating
- biosynthesis
- maturation
- release
How do viruses cause cancer?
activated oncogenes transform normal cells into cancerous cells
the genetic material of oncogenic viruses becomes integrated into the host cells DNA
latent viral infection
virus remains in asymptomatic host cell for long periods
may never manifest
cold sores, shingles
How can proteins be infectious
prions can be inherited or transmissible by ingestion, transplant, and surgical instruments
bacteriophage
virus that infects bacteria
capsid
protein container
capsomeres
single unit of capsid
DNA virus replication
happen in nucleus
RNA virus replication
happen in cytoplasm
Why are viruses not “alive”
require host cell for replication
do not have mechanism for ATP generation
persistent viral infections
disease process occurs over a long period, usually fatal
measles
