microbio ch 6
What are the 5 steps of the viral life cycle in order?
1) attachment 2) entry 3) synthesis 4) self-assembly 5) release
Select the three methods used by animal viruses to gain entry to host cells.
1) fusion of the viral envelope with host cell membrane 2) direct transfer of viral nucleic acid into the cell 3) endocytosis of the virus into the cell
The simplest viruses consist of nucleic acid surrounded by a protein coat. This composite structure of viral nucleic acid and protein is called a...
nucleocapsid
The main difference between virulent phages and temperate phages is that virulent phages...
only have a lytic cycle
Proteins synthesized by a virus are classified as structural or nonstructural. A nonstructural protein...
participates in the viral life cycle but is not a part of the mature virion
Which two of the following events occur during viral entry?
penetration and uncoating
Viruses can be quantified using a lawn of cells and counting the number of clear spots where the cells were lysed by viruses. This type of assay is called a(n)...
plaque assay
Infectious agents composed entirely of protein are called...
prions
Which two of the following components make up a viral nucleocapsid?
protein coat and nucleic acid
Prions are composed of..
protein only
what are prions composed of?
protein only
Protomers
proteins that make up the capsid
What term describes the host cell component that a virus will bind for attachment?
receptor
A virus will attach to a host cell via a viral ______ and a host receptor
spike
what are viroids composed of?
ssRNA
Which viral life cycle step generally occurs immediately after the virus has uncoated?
synthesis
Which of the following describes a bacteriophage that may either lyse its host cell or remain within the cell without lysing it?
temperate
Is RNA or DNA quicker to mutate?
RNA
Once a virus enters the cytoplasm of a host cell, which step would occur next?
Replication of the viral genome
Which of the following could be the genome of a single virus?
a) dsRNA b) ssDNA c) dsDNA d) ssRNA
Capsid
another term for the protein coat
The first step in a typical viral life cycle is...
attachment
The viral life cycle begins when the virus and host first meet, in a step termed...
attachment
Proteins synthesized by a virus are classified as structural or nonstructural. A structural protein...
becomes a part of the mature virion
Enveloped viruses use _______
budding
virion
complete viral particle
In contrast to viral genomic DNA, which may be dsDNA, ssDNA, dsRNA, or ssRNA, cellular genomes are always..
double stranded DNA
The second step of the viral life cycle is...
entry
The outer lipid membranous layer found surrounding some viruses is called the...
envelope
naked vs enveloped
enveloped has and envelope along with nucleic acid and protein
The energy for viral replication, gene expression, and nucleocapsid assembly comes from...
host ATP
A bacterial plaque assay requires the use of a...
lawn of cells
What is the general term used to describe the viral component that binds to a host cell for attachment?
ligand
A viral envelope is composed of primarily
lipids
Nonenveloped viruses________ the host cell
lyse
Which two mechanisms are used by some virions to enter an animal cell?
macropinocytosis and endocytosis
virus is composed of?
nucleic acid and protein
What types of viruses can use endocytosis as a means of viral entry?
Both enveloped and naked viruses
Which type of viral genome uses only host enzymes to replicate?
DNA
Which of the following best describes viral tropism?
the specific cell type that a virus can infect
Some viruses infect specific tissue types but not others. This is called...
tropism
Viral specificity for a host cell type is dependent on:
viral ligand and host receptor
A mature virus particle assembled from all of its components is referred to as a
virion
Which of the following is the study of viruses?
virology
In the context of virus replication, fusion with the host cell membrane, direct transfer of nucleic acid, and endocytosis are the three modes of....
virus entry to host cell