Exam 2 Viral Replication Flashcards
The few genes that a virus has codes for what?
Viral components and the enzymes needed for replication
Who are the majority of enzymes a virus needs supplied by?
The host cell
In order to successfully replicate the virus must take over what?
The host cells metabolism
What is a bacteriophage and what else is it known by?
A virus that attacks bacteria also known as a phage
What is the first stage of a bacteriophage lytic cycle?
Attachment
The virus attaches itself to complementary site on the bacterial cell wall with a weak attachment
The second stage of the bacteriophage lytic cycle
Penetration
The phage releases viral lysosome to destroy the bacterial cell wall
The tail sheath penetrates the cell wall
The viral nucleic acid is injected into the bacteria
What is the shape of a bacteriophage tail sheath
Rocket ship shape
What is the third stage of a bacteriophage lytic cycle?
Biosynthesis
The phage use the host free nucleotides to make several copies of viral DNA or RNA
This is the time of the eclipse period where for the first several minutes after injection of the nucleic acid into the bacterial cell, there will be no visible particles
What is the fourth stage of bacteriophage lytic cycle?
Maturation
During this phase the virus nucleic acids and capsids are assembled
Phage heads and tails are assembled with protein subunits
What is the 5th and final stage of the bacteriophage lytic cycle
Release
Cell membrane to the bacterial cell will lyse due to the production of bacterial lysozymes killing the host cell
Newly released phages are free to infect other cells
What starts the bacteriophage lysogenic cycle?
The phage penetrates the bacterial cell
Linear DNA becomes circular in order to incorporate viral DNA into bacterial
The insertive viral DNA is called the prophage
What happens in the bacteriophage lysogenic cycle after the prophage
The viral phage genes are latent or inactive and therefore are not replicated immediately
oncoviruses are considered to be latent viruses
As a cell replicates his DNA, it will also replicate viral DNA
What happens in bacteriophage lysogenic cycle after the viral DNA has been replicated third step
phage conversion
The whole cell may exhibit new properties often becoming virulent or resistant antibiotics
What happens after phage conversion of the bacteriophage lysogenic cycle four step
Specialized transduction
Newly formed viral particles will contain both bacterial and viral DNA
When this virus infects a new host, it will not only incorporate its DNA into the new host but also the previous host DNA as well
Viruses mutate quickly because of this feature in the bacteriophage lysogenic cycle
Specialized transduction
Replication of animal viruses step 1
Attachment
Virus has attachment sites that bind to receptors on animal cells
Such as dendritic cells in the vaginal Canal
Replication of animal viruses step 2
Entry
Most viruses enter the cell via receptor-mediated endocytosis
Or
Enveloped viruses will enter the cell by fusion
What is fusion in replication of animal viruses?
Fusing their outer covering or envelope with the host cell membrane and then releasing the capsid into the host
Example is HIV
Step 3 of replication of animal viruses
Uncoding
The viral DNA is separated from its protein coat using host enzymes
Step 4 of replication of animal viruses
Biosynthesis
DNA viruses replicate in the nucleus of the host cell using the host enzymes to build new capsids
Examples include common cold, smallpox chickenpox warts
RNA viruses. Use reverse transcriptase to make DNA from RNA, then incorporate that DNA into the hosts in order to make several copies of viral nucleic acid
May lay latent at this stage
Examples of latent viruses
Hiv 10 years
Rabies 6 years
Polio and respiratory viruses
Fifth and last stage of replication of animal viruses
Maturation and release
Viral capsule is assembled
Virus pushes through the cell membrane of the animal cell collecting phospholipids on its surface. This new lipid covering is called an envelope
