Chapter 8 (from quizlet) Flashcards
Host specificity of a virus is determined by what?
interactions between viral attachment proteins and host cell receptors
What binding determines the ability of a virus or bacteriophage to specifically attach to a host cell occurs through the interactions of the viral attachment protein with the host cell receptor?
the host range
Antiviral drugs that act at the level of host recognition are designed to do what?
prevent virus binding to the cell receptor
HIV enters the cell through what type of mechanism?
membrane fusion
the influenza virus gains entry into a host cell how?
by receptor-mediated endocytosis
How do plant viruses often gain entry into host cells?
by injury caused by insects to host cells
What is the mode of action for fuzeon? (an antiviral drug that prevents membrane fusion for entry into the cell by HIV)
to bind to gp41 membrane fusion protein of HIV
The Baltimore classification scheme classifies viruses based on their mechanism of mRNA synthesis in how many classes?
7
Class I viruses, double-stranded DNA viruses, usually utilize what polymerases for mRNA synthesis of DNA replication?
host cell DNA-dependent RNA polymerase and host cell DNA-dependent DNA polymerase
Class III viruses, double-stranded RNA viruses, utilize what polymerase for genome synthesis?
viral RNA-dependent RNA polymerase
Class V viruses, negative sense-stranded RNA viruses, utilize what polymerase for mRNA synthesis?
viral RNA-dependent RNA polymerase
For most double-stranded DNA eukaryal viruses, DNA replication occurs in the ___ and translation occurs in the ____.
nucleus, cytoplams
A bacteriophage genome that is integrated into the bacterial chromosome is called what?
a prophage
Phage lambda is referred to as a temperate phage. What is a temperate phage?
A phage that can undergo either a lytic or lysogenic phase of replication.
Protease inhibitors are routinely used in the treatment of an HIV infection to slow down the progression of the disease..How do these inhibitors work?
They inhibit the proteolytic modification of the viral capsid to form an infectious virion
How do most enveloped viruses exit the cell?
by budding
What is the method of assembly of the intact virion of the tobacco mosaic virus?
the capsid proteins assemble around the viral nucleic acid
Bacteriophage T4 lyses the bacterial host cell for release of newly formed virions. The cell wall of the bacterium is broken down by this virally encoded enzyme..
lysozyme
Many antiviral drugs are nucleoside analogs. The nucleoside analogs primarily target what enzyme?
viral nucleic acid polymerases
AZT is a nucleotide analog used to treat people infected with what?
HIV
The viral attachment protein specifically binds to a host cell receptor. What are examples of host cell receptors?
proteins, glycoproteins, lipopolysacchardes, sialic acids
The second step in viral replication is entry. What is the entry for bacteriophage?
direct entry of the nucleic acid into the cell
Class VII viruses, double-stranded DNA viruses that utilize reverse transcriptase, replicate the genome using what polymerase?
host cell DNA-dependent RNA polymerase
What is the reason nucleoside analogs are effective against viral nucleic acid polymerases?
because viral polymerases have a high affinity for incorporation of the analogs
The enzyme ___ has a high affinity for AZT and will incorporate it into a newly synthesized DNA strand. This effectively terminate DNA replication because the incoming nucleotide cannot be bound to AZT.
viral reverse transcriptase
An HIV mutant has been identified that is resistant to the drug AZT. most likely the mutation occurred in the viral gene that encodes for what?
reverse transcriptase
