Chapter 13 LearnSmart
Infections that have a sudden onset of symptoms of relatively short duration are described as ________.
Acute
The study of viruses is important because ___________.
Bacteriophages play a significant ecological role in reducing bacterial populations in nature, there are many medically important viruses that cause disease, viruses can be a vehicle for horizontal gene transfer in bacteria
A viral capsid is made up of subunits called _____________.
Capsomeres
Which of the following are classified as persistant infections?
Chronic infections and latent infections
True or False: Lysogens are more susceptible to reinfection by the same type of phage
False
True or False: Most bacteria engulf bacteriophages as part of the phage replication strategy
False
__________ phages cause productive infections that do not kill the host cell.
Filamentous
Late proteins of the T4 lytic cycle include __________.
T4 capsomere components and T4 tail fibers
_________ phages have the option of entering the prophage state, while ___________ phages always burst the host cell shortly after infection.
Temperate; lytic
Which facts best support the position that viruses are not living organisms?
Viruses are inert outside of a host and viruses cannot reproduce on their own.
What is a true statement about viruses?
Viruses contain RNA or DNA but not both and the viral capsid is composed of protein
The number of phage particles released from a host cell is called the _________ size.
burst
Viral genomes can be _________.
either single-stranded or double-stranded
Viral genomes can be ____________.
either single-stranded or double-stranded
M13 particles are assembled during a process called _________, which the virus uses to exit the cell.
extrusion
True or False: There is no need to classify viruses because they are not living organisms.
false
The term ____________ is used to describe the rupture or bursting of a cell.
lysis
One of the early proteins expressed in the T4 lytic cycle is an enzyme called a _______ that degrades the bacterial DNA.
nuclease
In which type of infection does the virus remain in the host for years, sometimes without symptoms?
persistent
What are the three general shapes of most viruses?
Complex, helical, icosahedral
What directs the incorporation of phage DNA into a bacterial chromosome?
integrase
Lysogens are protected against infection by the same phage because the phage-encoded repressor protein binds to the ___________ on the incoming phage, preventing expression of the phage genes.
operator
At a minimum, all viruses are composed of __________.
proteins and nucleic acids
Which facts best support the position that viruses are not living organisms?
Viruses cannot reproduce on their own and viruses are inert outside of a host
Rank the following by size, from smallest to largest: human cells, viruses, bacteria.
Viruses, bacteria, human cells
The term ________ is used to describe the rupture or bursting of a cell.
lysis
A ____________ is an animal virus genome residing silently in a host cell genome.
provirus
Virus infections that result in the information of new virus particles are described as _____________.
productive
A virus acuired by inhalation would be called a(n) _____________.
respiratory virus
Symptoms of acute viral diseases result from __________.
Host immune response and host tissue damage
Tumors are abnormal growths that result from a malfunction in the regulation of ________.
cell growth
In the lytic cycle of the T4 page, lysozyme degrades a portion of the bacterial ____________.
cell wall
The hepatitis B virus sometimes causes an infection that results in a continuous and low-level production of virus particles. This type of infection pattern is specifically described as a(n) _____________ viral infection.
chronic
The hepatitis B virus sometimes causes an infection that results in a continuous and low-level production or virus particles. This type of infection pattern is specifically described as a(n) __________ viral infection.
chronic
The M13 phage has a single-stranded DNA genome. Its replicative form is a double-stranded DNA molecule. The second strand of DNA is synthesized by ________.
host DNA polymerase
Consequences of lysogeny include _________.
immunity to superinfection and lysogenic conversation
Consequences of lysogeny include _____________.
immunity to superinfection and lysogenic conversion
Describe viruses
infectious agents
How does bacteriophage nucleic acid enter the host cell?
injection
Viral proteins that stick out from the viral envelope or capsid and attach to host cell receptors are termed __________.
spikes
Phage DNA and proteins are made during the _________ stage of the T4 lytic cycle.
synthesis
The study of viruses is important because ______.
there are many medically important viruses that cause disease, bacteriophages play a significant ecological role in reducing bacterial populations in nature, and viruses can be a vehicle for horizontal gene transfer in bacteria
The major categories of animal viral infections are _________ infections, characterized by the sudden onset of symptoms of a relatively short duration, and _________ infections that can continue with or without symptoms for years.
Acute; persistent
Match each possible outcome of phage replication with the correct definition: productive infection and latent state.
Productive infection: new viral particles are produced Latent state: viral genome remains silent within the cell
True or False: Bacteriophages are important medically because they can be used to prevent the growth of food-contaminating pathogens
true
Which are two main criteria used in classifying viruses?
Genome structure and host range
Match each tumor to the correct statement: malignant and benign.
Malignant: spreads to nearby tissue Benign: does not spread to nearby tissue
________ infections remain for years, or even the lifetime of the host, sometimes without any symptoms.
Persistent
Viruses that infect bacteria are called __________.
Phages; bacteriophages
Match each gene type with the correct description: proto-oncogene and tumor suppressor gene.
Proto-oncogene: stimulates cell growth Tumor suppressor gene: inhibits cell growth
Which of the following are viral protein components that attach to specific receptors on host cells?
Tail fibers and spikes
Viruses are challenging to study because ________.
They can only be seen using an electron microscope and they are obligate intracellular parasites
To maintain the lysogenic state, a ________ protein prevents expression of the gene required for excision.
repressor
The binding of a bacteriophage surface protein to a host cell receptor is called ________.
attachment
Some pathogenic bacteria produce toxins that are encoded on prophage DNA, and these are examples of ___________ conversion.
lysogenic
Which of the following describes a consequence of lysogeny that could result in human disease?
lysogenic conversation
In enveloped viruses, sandwiched between the nucleocapsid and the envelope is the __________.
matrix protein
Which of the following occur during the synthesis stage of the T4 lytic cycle?
synthesis of phage DNA, degradation of bacterial DNA, synthesis of phage proteins