Mod 6 Ch. 17 Flashcards
What are common features found in all viruses?
Nucleic acid surrounded by a protein capsid
Viral genomes can be..
DNA or RNA
Single-stranded or double-stranded
Linear or circular
Which of the following is a common order of steps for a viral reproductive cycle?
Attachment, entry, integration, synthesis of viral components, viral assembly, viral release
An example of an emerging virus is..
- a coronavirus that causes SARS
- HIV that causes AIDS
- a strain of influenza virus called H1N1 that causes the flu
A mutation in phage lambda results in 10-fold greater transcription of the cll gene. How do you think this mutation would affect the reproductive cycles?
The lysogenic cycle would be favored
The cl gene that encoded the lambda repressor has two promoters designated PRE and PRM. Which of the following statements is false?
PRE is activated by the lambda repressor
What features vary among different types of viruses?
Their genomes
Size, RNA versus DNA, single-stranded versus double-stranded
Complexity of their capsids and whether or not they contain an envelope
During which step may a virus remain latent?
Following its integration into the genome of the host cell
Which cycle produces new phage particles?
Lytic cycle
What is meant by the term “emerging virus”?
Viruses that have arisen recently and are more likely to cause infection compared with previous strains
Let’s suppose a drug inhibits the function of the N protein. Would such a drug favor the lysogenic cycle, favor the lytic cycle, or prevent both cycles from occurring?
Neither cycle could be followed
What is the function of PRM?
This promoter is used to express the lambda repressor during the maintenence of the lysogenic cycle
What environmental conditions favor a switch to the lytic cycle?
An adequate supply of nutrients or UV light
