Micro Chapter 13
Please choose the term that describes a virus that has a lipid bilayer (derived from the host cell) surrounding its capsid.
Enveloped virus
In the lysogenic stage of phage replication, the host cell is lysed.
FALSE
Considering the three distinct locations of PRRs on or in cells, the PRRs ________ would be most likely to detect replicating viruses
In an infected cell's cytoplasm
Which of the following about viruses/viral infections is FALSE?
Phages often enter a cell via receptor-mediated endocytosis.
The enzyme lysozyme is used by the T4 phage to assist in the injection of its DNA into the target cell.
TRUE
A bacteriophage initially associates with which bacterial structure?
The bacterial cell wall
Viral spikes
attach specifically to host cell receptors.
Expression of viral oncogenes in infected animal cells
can mimic proto-oncogenes, causing imbalance in cell cycle control towards unchecked proliferation, leading to tumor formation.
The main reason that blood proteins and phagocytic cells can enter infected tissues during the inflammatory response is that
changes in the cells lining the blood vessel walls allow the items to leave the bloodstream and enter the infected area
During inflammation, __________ system proteins leak out into tissues to become cleaved and activated and attack microbes
complement
Every virus particle contains
either DNA or RNA
The mechanism of exit for an animal virus is primarily determined by whether or not the virus has a(n) _____.
envelope
The phages T4 (lytic) and lambda (temperate) share all of the following characteristics EXCEPT Causing productive infections that involve host cell lysis Having a DNA genome attaching via a receptor on the bacterial cell surface having a nucleocapsid existing as a prophage injecting their genome into host cell
existing as a prophage
A major difference in the replication of animal viruses and bacteriophages is the ______ step.
penetration
Once inside the host cell, viral DNA directs production of _______.
new viral particles
Peristalsis in the intestines is
the contraction of smooth muscle elements in the intestine to propel food, liquid, and microbes along (and ultimately out) of it
Some phages are medically important for all of the following reasons EXCEPT
they also infect eukaryotic
Removal of the capsid to release the virus nucleic acid into the host cytoplasm is called ______.
uncoating
Rabies virus, which can be transmitted from animals to humans, is classified as a(n)
zoonotic
Which of the following is used to classify viruses? i. Nucleic acid ii. Shape iii. Size iv. Host range v. Biochemical tests
(i), (ii), (iii), and (iv)
What term describes the type of bacteriophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide?
Lysogenic
Molecules called ___________ __________ receptors (PRRs) allow the body's cells to "see" signs of microbial invasion
Pattern Recognition
Which of the following contains only one type of macromolecule? i. RNA viruses ii. DNA viruses iii. Prions iv. Viroids v. RNA and DNA viruses
(iii) and (iv)
After beta phage infects Corynebacterium diphtheriae and integrates its DNA into the host genome, the bacterium is capable of causing the disease diphtheria. Which term best describes this phenomenon?
Lysogenic conversion
What term describes the type of bacteriophage infection in which the host bacteria are lysed and killed as a result of the infection?
Lytic
PRRs are located in three distinct locations on or in the cells, namely
On the cell surface, in the cytoplasm, in endosomes or phagosomes
In viral entry by endocytosis
the host cell's cytoplasmic membrane surrounds the whole virion and forms a vesicle.
Which of the following is an example of lysogenic conversion?
A lysogen that acquires new characteristics as a result of the prophage.
Immunity to superinfection (infection of a cell at a later time with a second, identical bacteriophage) is a consequence of lysogeny. Why does this occur?
A repressor produced by the first virus will actively suppress the lytic cycle of the second virus.
Which of the following is required to maintain a lysogenic state?
A repressor protein
In lytic phage infections, the early viral proteins are important for initial steps of phage multiplication. Which of the following are functions of these proteins?
-Degrade host cell's DNA. -Modify host cell's RNA polymerase so that it doesn't recognize bacterial promoters. -Degrade host cell's ribosomes. -Activate bacteriophage's DNA polymerase for copying bacterial RNA.
You discover a new medication that prevents the activity of RNA-dependent RNA polymerase. Which of the following will be affected by this medication?
-Ebola virus -Polio viruses
Bacteriophage MS2 is an icosahedral, (+) sense, single-stranded RNA phage. It infects E. coli and other members of the Enterobacteriaceae. It only infects strains of these bacteria that have produced a sex pilus. Based on the information given, which of the following are true about MS2?
-The bacterial receptor for MS2 is on the F (sex) pilus. -MS2 is a virulent phage. -The phage carries a replicase. -MS2 can only infect F+ bacteria.
Which of the following characterizes phage but NOT eukaryotic viruses?
-The genome, but not the protein coat, enters the cell. -They may be involved in generalized or specialized transduction.
A granuloma
-contains T cells -contains macrophages -walls off materials that cannot be destroyed -is an example of cooperation between innate and adaptive immune responses
Place the steps of T4 phage replication into the correct sequence.
ATTACHMENT: Phages attach to receptors on bacterial surface GENOME ENTRY: Phage tail contracts and phage DNA is injected into bacterial cell SYNTHESIS: Phage genome is transcribed and translated; phage DNA is replicated ASSEMBLY: Newly synthesized phage components are assembled into mature virions RELEASE: Bacterial cell lyses, releasing new infectious virions
Which of the following descriptions fits a chronic viral infection?
Characterized by continuous production of low levels of viral particles, potentially even in the absence of active symptoms of disease. The organism is usually still highly infectious during this time.
How does bacteriophage DNA get into the host cell?
It is injected.
Which of the following describes a latent viral infection?
Long periods of time with essentially zero viral replication, punctuated by outbreaks of active replication and disease manifestation. Infected individuals are largely non-infectious between outbreak periods.
When present, of what is the viral envelope composed?
Mainly lipids
Which of the following can cause a phage in the lysogenic stage to revert to the lytic stage?
Ultraviolet light
Please choose the statement that best describes the role of viral surface proteins or spikes.
Viral spikes provide means of attachment to host cell surface.
A consequence of the temperate life cycle is lysogenic conversion. What does this term mean?
When a bacterial cell starts to produce a new phage protein (e.g., diphtheria toxin) after the viral genome inserts into the host genome.
The capsid of a virus is
a protein shell that surrounds the nucleic acid.
C3a & C5a
activated members of the complement system that can cause inflammatory changes in blood vessels
The general steps in viral replication (in order) are
adsorption, penetration, synthesis, assembly, release.
Influenza viruses bud from the host cell. Based on this information, the viruses most likely
are enveloped
A virus usually infects only certain types of cells due to
interactions between viral and cellular surface molecules.
The final step in T2 bacteriophage infection results in:
lysis of the bacterial cell and release of new viral particles
Viral cycles that end in release of the new phages and immediate destruction of the host bacterial cell are referred to as ______.
lytic
Viral capsids are composed of ______.
protein
Phage DNA encodes for the proteins of the viral capsid and
regulatory proteins that direct the production and assembly of the capsid proteins.
All of the following could serve as receptors for phage attachment EXCEPT
ribosomes.
The stage of T4 replication that involves interaction between the protein fibers on the phage and receptors on the bacterial cell wall is the
attachment stage.
The combination of antibody and antigen bound together is called a(n) ________, and it is required to begin the classical pathway of complement activation
immune complex
If a macrophage's pattern recognition receptors detect bacterial products, then that macrophage will produce _________.
pro-inflammatory cytokines
Antibiotics disrupt the normal microbiota and can predispose a person to infections caused by
-Candida albicans growing in the intestinal tract -Clostridium difficile growing in intestine
Which of the following characteristics can be utilized to classify and categorize viruses?
-Type of nucleic acid -Hosts infected -Strandedness of nucleic acid (positive/negative sense) -Capsid shape -Presence or absence of envelope -Disease symptoms
C3
-splits C3 -Forms at the convergence of the three pathways of complement activation
Match each word/phrase with its definition.
1. VIRULENT PHAGE: Phage that lyses the bacterial host when completing its life cycle 2. SPECIALIZED TRANSDUCTION: Transduction resulting from an error in excision of a prophage 3. ACUTE INFECTION: Infection in which a virus multiplies rapidly and spreads in the host 4. TEMPERATE PHAGE: Phage that is able to incorporate its genome into the host chromosome 5. GENERALIZED TRANSDUCTION: Transduction resulting from a packaging error
What bacterial enzyme is used by the virus for replicating its nucleic acid?
DNA polymerase
The T-even bacteriophages such as T2 and T4 infect
Escherichia coli.
Once a phage becomes lysogenic, it will remain lysogenic and never be lytic again.
FALSE
T-even phages can replicate independently of a host cell.
FALSE
Toll-like receptors (TLRs) can be found ________ of macrophages.
In endosomes, on the cell surface, in phagosomes
Viruses with which characteristic would be expected to have a higher mutation rate?
RNA genome
Almost immediately upon entry, the viral nucleic acid alters the gene expression of the host cell.
TRUE
Bacteriophage DNA directs the degradation of the bacterial host cell's DNA.
TRUE
Both enveloped and non-enveloped (naked) viruses can enter a cell by endocytosis.
TRUE
The PRRs of an innate immunity cell allow that cell to tailor its response according to the general category of pathogen by determining
The assortment of the pathogen's MAMPs
A bacterium being examined in a microbiology laboratory is found to be lysogenized by phage A. Which of the following statements is TRUE?
The bacterium exhibits a new genotype but may not exhibit a new phenotype.
