Chapter 13 Flashcards
Louis Pasteur did what?
Coined term virus
Latin for poison
Characteristic of viruses
Obligate intercellular parasite Need host to multiple Submicroscopic Noncellular Contain DNA or RNA Protein coat Lack enzymes for ATP
Iwanowski and Beijernick
Discovered tabacco mosaic virus
Low leaflet and frosch
Discovered foot and mouth disease in cattle
Structure of viruses
DNA or RNA not both
Single or double stranded
Needs to enter host
Protected by capsid
What’s the capsid do?
Protein shell that surrounds nuclei acid
What is capsomere?
Sub unit of capsid that self assemble to form capsid
What is a naked virus mean?
No envelope
What is the envelope ?
Lipid structure that surround capsid
What are the spikes?
Project from envelope
Helps the virus adhere
Helical what is it??
Rod shape of the capsid
What is the polyhedral of the capsid?
20sided
3D appearance
Ex. Poliovirus, herpes, and adenovirus
What is the complex of the capsid
Capsid is polyhedral and contact tile sheath is helical
Ex. Bacteriophage and pox virus
What is the host range?
Spectrum of host cells a virus can infect
Depends on viruses requirement for multiplication
Must be chemically react with host receptors sites
What’s does the capsid do of a t-even bacteriophage ?
Stores nucleic acid
What does the contractile sheath of a t-even bacteriophage?
Penetrates and inject nucleiac acid
What is the tail fiber of bacteriophage do?
For attachment
What do the structure of t even bacteriophage of tail pins?
Penetration of cell wall
What are the steps of the lyric cycle in T4 viruses ?
- Attachment
- Penetration/Entry
- Biosynthesis
- Maturation
- Release
what is attachement?
uses the host cell’s receptor sites (tail fibers)
what is penetration/entry?
Biral nucleic acid is injected into the host cell
what is biosynthesis?
each viral componet is made using host’s metabolic machinery
what is maturation?
viral components are assembled
what is release?
bacteria cell is full of virues, lyses, and dies
what is burst time?
time it takes from attachemetn to release
average time is 20-40 min
what is burst size?
number of viruses released per host cell
average is 200 viruses
viral multiplication in bacteriophage?
multiply in two ways
lytic and lysongenic
lytic cycle cells
end with lyse (death to host cell)
lysogenic cycle allows
host cell to remain alive
lysogenic cycle
incorporates a viral nucleic acid into host cell’s
phage remains inactive
everytime host replicate virues is
what is adverse conditions do to lysogenic cycle?
can cause the lysogenic cycle to end and lytic cycle to begin
what is the steps in lysogenic cycle?
- attachment
- pentiration/entry
- prophage created
- bacteria divides with prophage
what is prophage?
combination of bacterial and viral nucleic acids
if prophage begins outside of bacterial cells, virus will being lytic cycle
how do you grow bacteriophage in the lab?
- mix bacteria and virus in a soft agar solution and pour onto plate with solid agar
- incubate at 38 degrees celcius
- lawn of bacteria with plaque will apear
what is plaque?
were virus has killed bacteria
what is the process for multiplication in animal viruses
- attachment
- penetration
- uncoating
- biosythesis and assembly
- release
growing animal viruses in the lab
in live animal ;
some viruses can only exsist in animals
study the immune system response
growing animal viruses in embryonic eggs
viruses is injected into fertilized egg
viral growth is detected by death or damage to embryo
used to make vaccines
how do you identify viruses?
cytopahtic effects
serological tests
nucleic acids
what is serological tests?
detects antibodies against viruses in a patient
what is nucleic acids?
uses PCR to obtain enough nucleic acids to identify
taxonomy of virues
family
genus
species
family - virdae
genus - virus
species is common name of species
what are subspecies designated by?
number
example of taxonomy of viruses?
family ; herpesvirdae
genus; herpesvirus
species; human herpes virus
subspecies; HHV-1, HHV-2
what is adenovirdae?
common cold viruses
what is poxvirdae?
small pox or cow pox
what is orthomyxovirdae?
influenza viruses A, B, and C
herpesviridae?
cold sore, chicken pox
they are monoonucleosis
what is papvavirdae:
gential warts
cervic cancer
what is retrovirdae virus?
HIV
What are some extreme viruses?
ebola
causes fever, hemorrhaging and blod clotting
what is acute viral?
rapid onset of symptoms but not short lived
ex. influenza
what is latent viral infection?
virus remains asymtematic in host cell for long period of times
ex. cold sores and shingles
what is persistant viral infections?
disease occurs over long period of time
gennerally fatal
Ex. HIV/AIDS
what are ways to prevent viruses?
vaccines—> ex. rubella
antiviral drugs –> AZT
what is prions?
proteinaceous infection particles
cause neurolgical disease
Ex. Mad cow disease
