Discussion Questions Unit 2 Flashcards
An E. coli cell has a plasmid that contains the gene for resistance to chloramphenicol (an antibiotic). It becomes infected with a “lambda” bacteriophage (temperate) and transduction occurs. What might happen to other E. coli cells in the vicinity, as a result? Describe the process.
It can pass the resistance to chloramphenicol onto the other E. coli cells after replication
What would happen to phage lytic replication if the phage lysozyme is mutated so that it is now nonfunctional? (what does lysozyme have to do with phage lytic replication?)
(Lysozyme weakens the cell wall in order to inject its genetic information into the host cell)
No entry -> no phage replication
How does transduction benefit a bacterium? Explain how transduction could be used to cause a phenotypic change in a bacterial species
Transduction can lead to significant phenotypic changes in bacteria by enabling the transfer of beneficial traits, such as antibiotic resistance or new metabolic capabilities, which can enhance their survival and adaptability in various environments.
Phenotypic: resistance
What would happen to phage lytic replication if the attachment protein on the bacteria is mutated in such a way that it has completely changed shape?
No attachment -> no infection -> no phage replication
Some viral genomes, composed of single-stranded RNA, act as mRNA. What advantage might these viruses have over other kinds of viruses?
You can have immediate translation of viral proteins
What would be an advantage of phage therapy in treating bacterial infections?
Phages lyse the bacterial cell it targets
It will only attack bacterial cells
Might be effect against antibiotic resistant bacteria
Each phage attacks a specific type of bacterial strain
You don’t have to worry about secondary infections like with broad spectrum antibiotics that kill basically everything
An agricultural microbiologist wants to stop the spread of a viral infection of a crop like TMV. Is stopping viral attachment a viable option? Why or why not?
No, plant viruses need to enter through a wound of some sort made by an insect or instrument
What differences would you expect in the replication cycles of RNA phages from those of DNA phages?
RNA: Translated right away -> short infection cycle
DNA: rely on host for transcription & translation -> longer
DNA: Lysogeny
Although many +ssRNA viruses use their genome directly as messenger RNA, +ssRNA retroviruses do not. Instead, their RNA is transcribed into DNA by reverse transcriptase. What advantage do retroviruses gain by using reverse transcriptase?
dsDNA is more stable than RNA;
dsDNA can integrate into the host cell -> remains there for the lifetime of the cell
Why do you need to grow let’s say the Influenza virus in a chicken egg? (Think about what a virus is and how it reproduces itself)
It needs a host cell
If an enveloped virus were somehow released from a cell without budding, it would not have an envelope. What effect would this have on the virulence of the virus? Why?
Nonvirulent -> can’t attach or enter host;
Without glycoproteins or spike proteins the virus won’t be able to recognize and attach the host cell
Compare and Contrast animal and bacterial viral replication
Entry Mechanism: Animal viruses enter through endocytosis or fusion; bacteriophages inject their DNA.
Replication Location: Animal viruses may replicate in the nucleus
Cycles: Animal viruses can establish latency
Release Mechanism: Animal viruses can bud off
Use your knowledge of the life cycle of SARS-CoV2 life cycle. Given the following antivirals being tested for effectiveness against SARS-CoV, determine what step they trying to inhibit.
Remdesivir (inhibits RNA-dependent RNA polymerase): synthesis
Ritonavir (HIV protease inhibitor): process proteins for assembly
HIV replicates only in certain types of human cells, and one early problem in AIDS research was culturing those cells. Why are scientists now able to culture HIV?
They had to pump in more T helper cells over a time period so that every time a set of viruses got released, they would be able to infect new T helper cells and then they could collect those viruses in culture and sequence it
Use your knowledge of the life cycle of HIV. Given the following antivirals widely used, determine what step this medication targets.
Retrovir (blocks RT): Synthesis
Prezista (HIV protease inhibitor): Maturation
Maraviroc (CCR5 antagonist): Attachment (block co-receptor)
Biktarvy (combination integrase inhibitor + 2 RT inhibitors): Prevents integration into the host chromosome; synthesis (RT)
Symtuza (combination protease inhibitor + 2 RT inhibitors): Synthesis; Maturation
