9.23.2022. + 9.26.2022. Study Questions Flashcards
How do viruses attach to host cells? (2)
- phage: tail fibers
- animal viruses: spikes
How is the penetration step in the replication of phages different from that of animal viruses?
How does a temperate phage differ from a lytic phage?
T: doesn’t necessarily lyse
L: lyses the host
What would be the consequence if a temperate phage lost the ability to synthesize a repressor?
productive infection, like in the case of phage induction
Describe why phages are important to humans (2)
- they can control the spread of bacteria during storage, like we talked about in class with processed meats
- phages are also being looked into as an option to treat bacterial infections in humans.
What is lysogenic conversion?
change in phenotype of a lysogen as a consequence of the specific prophage it carries
How are phages grown in the lab?
plaque assays
What is reverse transcriptase?
enzyme that synthesizes DNA using RNA as a template
Why are virally-encoded polymerases significant medically?
they can be used as a target for antiviral drugs
What is a retrovirus?
have a (+)RNA genome and carry reverse transcriptase within the virion
Which group of viruses need to carry their own polymerase within the virion? Why?
ss(-)RNA and dsRNA
How does an enveloped virus acquire the envelope?
via budding
Review animal viral replication cycle steps for each type of virus from attachment to release
Describe two ways to quantitate animal viruses
- acute
- persistant
What are two outcomes from a temperate phage?
a bacteriophage that can either
1. direct a productive infection that leads to host cell lysis or
2. remain silent within the host as a prophage (phage DNA) that replicates along with the host cell genome.
What is a prophage?
integrated phage DNA
Describe the relationship between temperate phages and prophages
latent form of a temperate phage; the phage DNA has generally been inserted into the host’s chromosome.
what is a lysogen?
bacterial cell that is containing the prophage
how do phages attach to cells?
tail fibers
how do animal viruses attach to host cells?
spikes
what is an example of lysogenic conversion?
only strains of Corynebacterium diphtheriae that are lysogenic for a certain phage can synthesize the toxin that causes diphtheria.
if a toxin is encoded exclusively by phage genes…
then only bacterial strains that carry the prophage will synthesize the toxin
what group of viruses encodes reverse transcriptase?
reverse transcribing viruses
what happens in normal transcription vs. reverse transcription?
normal: RNA is synthesized from DNA template
reverse; DNA is synthesized from an RNA template
what is an acute virus?
sudden onset of symptoms, short duration
what is a persistent virus?
long duration, often without causing symptoms
what are the two types of persistent viruses?
chronic and latent
