Ch. 13 microbiology

Circular clearings (holes) caused by phage-induced lysis in a bacterial lawn are called ______

Plaques

what type of tumor does not spread to nearby tissue?

benign

what type of tumor spreads to nearby tissue?

malignant

One of the early proteins expressed in the T4 lytic cycle is an enzyme called a(n) ___________ that degrades the bacterial DNA

Nuclease

In the case of T-even phages, the burst size is about A. 5 per host cell. B. 200 per host cell. C. 1,000 per host cell. D. 1 per host cell.

B. 200 per host cell

The term __________ is used to describe programmed cell death, a process naked viruses sometimes trigger as a means of release

Apoptosis

T/F: when a bacterial culture is infected with a temperate phage, all particles of the phage will lysogenize their host

False

T/F: DNA viruses can only replicate when the host cell is replicating its own genome

False

T/F: plant and animal viruses begin their infection cycles by binding to specific receptors on the cytoplasmic membranes of the target cells

False

T/F: prion replication depends on the presence of protease

False

Viruses are classified based upon _______ structure and ______ range

Genome; host

Tumors result from a defect in the regulation of cell ______

Growth

Through the process of phage ________, a prophage is excised and enters the lytic cycle

Induction

The term ________ is used to descfie the rupture or bursting of a cell

Lysis

During prion replication, the infectious prion protein _______ interacts with the normal protein _______, causing it to misfold

PrPsc; PrPc

Changing or covering up the molecules on the surface of the bacterium to which the phage particle binds is called _________ ___________ ____________

Preventing phage attachment

HIV is described as a __________ because it replicates its RNA genome by using reverse transcriptase to produce a DNA intermediate

Retrovirus

What term describes the concentration of virus particles in a sample

Titer

T/F: All viruses must separate the nucleic acid from the capsid before replication.

True

T/F: Bacteria that have genes for restriction endonucleases also have genes for modification enzymes.

True

T/F: Filamentous virus is incapable of causing a lytic infection

True

T/F: double stranded RNA viruses carry their own replicase because the host cell cannot translate double-stranded RNA

True

Infection of bacteria by ________ phases always ends with the lysis of the host cell

Virulent

The mechanism of exit for an animal virus is primarily determined by whether or not the virus has a(n) _____. A. envelope B. reverse transcriptase C. attachment spike D. RNA genome E. DNA genome

A. Envelope

_______ infections remain for years, or even the lifetime of the host, sometime without any symptoms

Chronic

A virus usually infects only certain types of cells due to A. interactions between viral and cellular surface molecules. B. the speed with which it can enter these cells. C. particular genes that it shares with the infected cell. the presence or absence of a D. cell wall on the host cell. E. differences in size between the virus and the host cell.

A. Interactions between viral and cellular surface molecules

What term describes the type of bacteriophage infection in which the host bacteria are lysed and killed as a result of the infection? A. Lytic B. Transforming C. Hemorrhagic D. Lysogenic E. Oncogenic

A. Lytic

Prions affect the A. nervous system. B. gastrointestinal tract. C. lymphatic system. D. respiratory system.

A. Nervous system

The protein projections on the surface of a virus that are involved in attachment to the host cell are called A. spikes. B. suckers. C. hooks. D. cilia. E. pili.

A. Spikes

________ infections are characterized as having a sudden onset of symptoms of a relatively short duration

Acute

Which of the following is an example of lysogenic conversion? A. A lysogen that acquires new characteristics as a result of the prophage. B. A temperate phage that loses the ability to synthesize a repressor. C. A temperate phage that loses the ability to recognize a repressor. D. A lysogen in which the prophage excises from the chromosome and begins the lytic cycle.

A. A lysogen that acquires new characteristics as a result of the prophage

After a virus enters a cell, the nucleic aids separates from the protein coat, a process called _________.

Uncoating

A virus can only infect cells that have the ________ to which that virus specifically attaches.

Receptor

Modifying self DNA shortly after its produced, followed by using restriction endonucleases to digest DNA that lacks modification is called _________-__________ ___________

Restriction modification systems

RNA viruses have a higher mutation rate than DNA viruses because replicase lacks a _________ ability

Proofreading

A _______ is an animal virus which remains silent while integrated in the host genome or replicating as a plasmid

Provirus

Viroids characteristically are composed of A. dsDNA. B. dsRNA. C. ssDNA. D. ssRNA.

D. ssRNA

The number of phage particles released from a host cell is called the _______ size

Burst

If the label in box A is "cold sore," what is the label in box B? A. Shingles B. Chickenpox C. Cold sores D. Cold sores and shingles

C. Cold sores

Assembly of the T4 phage A. may involve the use of scaffolds. B. may involve some self-assembly. C. is completely self-assembly. D. is completely dependent on scaffolds. E. may involve some self-assembly AND may involve the use of scaffolds.

E. May involve some self-assembly AND may involve the use of scaffolds

T/F: Capsids are made of a number of capsomeres that are covalently bonded to one another

False

What is the suffix that represents a viral genus?

-virus

In virology, a plague is a(n) A. Hardened area with accumulation of capsid B. Cleaning in a lawn of bacteria C. Form of lysogenic conversation

B. Cleaning in a lawn of bacteria

Viruses with which characteristic would be expected to have a higher mutation rate? A. Enveloped virus B. DNA genome C. Non-enveloped viruses D. Genome containing both DNA and RNA E. RNA genome

E. RNA genome

What gene type stimulates cell growth?

Protozoa-oncogene

_________ transduction is the result of excision errors

Specialized

What gene type inhibits cell growth?

Tumor suppressor gene

A viral infection in which the viral genome is integrated into an animal host cell chromosome is categorized as a ________ infection

Latent

Which of the following are possible labels for A and B? A. Chickenpox (A) and shingles (B) B. Chickenpox (A) and chickenpox (B) C. Cold sores (A) and chickenpox (B) D. All the choices are correct.

A. Chickenpox (A) and shingles (B)

The activation of the SOS system in a bacterium infected with a prophage results in A. complete lysis of the bacterial culture AND destruction of the viral repressor through host protease activity. B. destruction of the viral repressor through host protease activity. C. complete lysis of the bacterial culture. D. destruction of the viral genes. E. mutation of the DNA.

A. Complete lysis of the bacterial culture AND destruction of the viral repressor through host protease actively.

Rabies virus, which can be transmitted from animals to humans, is classified as a(n) ________ virus. A. arbo- B. zoonotic C. respiratory D. enteric

B. Zoonotic

Why is it not surprising that AIDS patients frequently suffer a viral-induced tumor? A. The therapies for HIV are highly mutagenic, which may lead to cancerous states in people taking the drug regimen. B. Products of an active HIV infection are highly mutagenic-so, as a person's illness progresses, these mutagenic compounds build up and are more capable of inducing a cancerous state. C. The immune system's CD4+ T cells are directly responsible for elimination of tumor cells. HIV attacks them and eliminates them, making a person more susceptible to cancer. D. HIV genomes integrate into the host cell chromosome. This integration might result in loss of control of the cell cycle (also known as cancer).

D. HIV genomes integrate into the host cell chromosome. This integration might result in loss of control of the cell cycle (also known as cancer)

The phages T4 (lytic) and lambda (temperate) share all of the following characteristics EXCEPT A. Having a nucleocapsid B. Injecting their genome into host cell C. Having a DNA genome D. Causing producing infections that involve host cell lysis E. existing as a prophage

E. existing as a prophage

T/F: replication of a single stranded (-)RNA virus requires synthesis of a (+) RNA before new viruses can be produced

True

What type of infection is shown in the figure? A. Chronic B. Oncogenes C. Latent D. Acute

C. Latent

Please choose the statement that best describes the role of A. viral surface proteins or spikes. B. Viral spikes enable replication of the viral nucleic acid. C. Viral spikes allow viruses to bind to each other. D. Viral spikes provide means of attachment to host cell surface. E. Viral spikes provide means for viruses to exchange nucleic acid. F. Viral spikes inject viral nucleic acid into host cell.

C. Viral spikes allow viruses to bind to each other

In the __________ system, bacteria retain small portions of phage DNA from an infection and use it to recognize and block subsequent infection by the same phage

CRISPR

Which of the following is required for prion replication? A. DNA-dependent RNA polymerase B. RNA-dependent RNA polymerase C. DNA-dependent DNA polymerase D. Abnormal prion protein

D. Abnormal prion protein

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. The first virus is suppressing all of the biochemical activity of the cell. Therefore, the second virus can't produce any new viral particles. B. A repressor produced by the first virus will actively suppress the lytic cycle of the second virus. C. All of the resources in the cell are in use by the first virus, so there's nothing left for the second virus to use. D. The first virus seeks out and destroys the second competing virus.

B. A repressor produced by the first virus will actively suppress the lytic cycle of the second virus

Which of the following descriptions fits a chronic viral infection? A. 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. B. 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. C. Strong viral replication causing lysis of host cells. This can lead to a disease state shortly after infection, which is steadily eliminated by the host's immune responses. Long-term immunity is usually present after the infection is cleared.

B. Characterized by continuous production of low levels of viral particles, potentially even in the absences of active symptoms of disease. The organism is usually still highly infectious during this time

What are the molecules that viral spikes attach to on the host cell typically composed of the following? A. Lipoproteins B. Glycoproteins C. Nucleic acids

B. Glycoproteins

Influenza vaccines must be changed yearly because the viral antigens change from year to year. Based on this information, which of the following is most likely true about the influenza virus? A. It has a DNA genome. B. It has an RNA genome. C. It is a naked virus. D. It causes a persistent infection. E. It is an enveloped virus.

B. It has an RNA genome

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? A. Oncogenic B. Lysogenic C. Transforming D. Hemorrhagic

B. Lysogenic

A temperate phage A. may be lysogenic. B. may be lysogenic AND enters a lysogenic or lytic life cycle shortly after entering the host cell. C. may be lytic. D. are all RNA viruses. E. enters a lysogenic or lytic life cycle shortly after entering the host cell.

B. May be lysogenic AND enters a lysogenic or lytic life cycle shortly after entering the host cell

Viruses A. have no effect on the number of bacteria. B. probably keep the numbers of bacteria in check AND are active in passing DNA from one bacterium to another. C .probably keep the numbers of bacteria in check. D. increase the number of bacteria. are active in passing DNA from one bacterium to another.

B. Probably keep the numbers of bacteria in check AND are active in passing DNA from one bacterium to another

The terms helical, icosahedral, and complex refer to A. viral life cycles. B. shapes of viruses. C. forms of nucleic acid. D. types of viral envelopes.

B. Shape of viruses

Which of the following descriptions fits the definition of a viroid? A. Nucleic acid material surrounded by a protein coat B. Single-stranded RNA molecules forming a closed ring C. Nucleic acid material surrounded by a phospholipid membrane D. Nucleic acid material surrounded by a phospholipid membrane and cell wall. E. Protein only, no nucleic acid or lipid components

B. Single-stranded RNA molecules forming closed ring

Some phages are medically important for all of the following reasons EXCEPT A. they can destroy bacterial cells. B. they also infect eukaryotic cells. C. they serve as a model for general viral replication cycles. D. their genome may encode a toxin.

B. They also infect eukaryotic cells

A consequence of lysogeny is lysogenic conversion. What does this term mean? A. When one bacterial species is converted into another species by the virus. B. When a bacterial cell starts to produce a new phage protein (e.g., diphtheria toxin) after the viral genome inserts into the host genome. C. When all biochemical processes in the lysogenized cell are converted into mechanisms of producing new viral particles. D. When the virus converts the bacterial cell into the lysogenic state to carry the viral genome long-term.

B. When a bacterial cell starts to produce a new phage protein after the viral genome inserts into the host genome

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 A. (i), (ii), (iii), (iv), and (v) B. (ii) and (iii) C. (iii) and (iv) D. (i), (iii), and (v) E. (i) and (iv)

C. ( iii) and ( iv)

Influenza viruses bud from the host cell. Based on this information, the viruses most likely A. Are non-enveloped B. Have a latent state C. Are enveloped D. Form a provirus

C. Are enveloped

Lysogenized cells A. are immune to infection by the same virus. B. may have new properties. C. are immune to infection by the same virus AND may have new properties. D. are immune to any further infection by any virus. E. respond to infection with the SOS response.

C. Are immune to infection by the same virus AND may have new properties

The correct order for the stages of a phage infection is: A. transcription, attachment replication of nucleic acid and protein, assembly, penetration, release. B. penetration, transcription, attachment, replication of nucleic acid and protein, assembly, release. C. attachment, penetration, transcription, replication of nucleic acid and protein, assembly, release. D. attachment, replication of nucleic acid and protein, penetration, transcription, assembly, release.

C. Attachment, penetration, transcription, replication of nucleic acids and protein, assembly, release

Expression of viral oncogenes in infected animal cells A. can mimic tumor suppressor genes, imbalancing cell cycle control towards unchecked proliferation, leading to tumor formation. B. checks the activity of tumor suppressor gene products, preventing tumor formation. C. can mimic proto-oncogenes, causing imbalance in cell cycle control towards unchecked proliferation, leading to tumor formation. D. checks the activity of proto-oncogenes and prevents tumor formation.

C. Can mimic protooncogenes, causing imbalance in cell cycle control towards unchecked proliferation, leading the tumor formation

Bacteriophages and animal viruses A. both may enter a host cell by fusion. B. both involve entry of the entire nucleocapsid. C. differ because bacteriophages leave the capsid outside the cell, while animal virus entry involves the entry of the whole nucleocapsid. D. both may enter a host cell by endocytosis.

C. Differ because bacteriophages leave the capsid outside the cell, while animal virus entry involves the entry of the whole nucleocapsid

Please choose the term that describes a virus that has a lipid bilayer (derived from the host cell) surrounding its capsid. A. Encapsulated virus B. Non-enveloped (naked) virus C. Enveloped virus D. Coated virus E. Icosahedral virus

C. Enveloped virus

Which of the following describes a latent viral infection? A .Strong viral replication causing lysis of host cells. This can lead to a disease state shortly after infection, which is steadily eliminated by the host's immune responses. Long-term immunity is usually present after the infection is cleared. B. 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. C. 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.

C. 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

Which of the following about viruses/viral infections is FALSE? A. The virus that causes chickenpox can establish a latent infection. B. Viruses are generally not considered to be "alive." C. Phages often enter a cell via receptor-mediated endocytosis. D. The virus that causes genital herpes can establish a latent infection.

C. Phases often enter a cell via receptor-mediated encocytosis

All of the following could serve as receptors for phage attachment EXCEPT A. pilus. B. flagellum. C. ribosomes. D. cell wall.

C. Ribosomes

Which of the following statements about specialized transduction is TRUE? A. The host cell is killed. B. It is a result of a packaging error. C. Specific DNA is transferred. D. It transfers RNA from one cell to another.

C. Specific DNA is transferred

What term is used to describe the viral proteins which protrude from the envelope and aid in attachment to host receptors? A. Capsomers B. Necleocapsid C. Spikes D. Capsids

C. Spikes

Why is it that abnormal forms of prion self-proteins can accumulate over time in the central nervous system, leading to disease? A. The abnormal forms actively degrade normal host cell proteases. B. There are no clearance mechanisms in place in the central nervous system. C. The abnormal forms are resistant to normal cellular protease degradation. D. Their buildup is so rapid that normal clearance mechanisms can't keep up.

C. The abnormal forms are resistant to normal cellular protease degradation

Insertion of small fragments of phage genome into host chromosome, giving the cell a "memory" of previous attempted infection and a way to recognize and destroy that foreign DNA in the future is called _________ system

CRISPR system

Regarding phage replication, A. when integrated into host DNA, the phage DNA is called a prophage. B. lambda is a good example of a temperate phage. C. the majority of phages are temperate. D. All of the choices are correct.

D. All of the choices are correct

Please choose the statement that describes how cytopathic effects are detected in virally infected cells. A .Performing immunological tests on infected cells B. Growing infected cells in a variety of different media C. Performing biochemical tests on infected cells D. Examining infected cells with a microscope

D. Examining injected cells with a microscope

The clustered, regularly interspaced short palindromic repeats (CRISPR) system in bacterial cells has been called the "immune" system of bacteria. CRISPR protect bacteria from a repeat infection from the same phage because bacterial cells A. integrate fragments from the phage DNA in their own chromosomes and target for destruction any DNA that contains the same fragments in the future. B. recognize proteins on the surface of the phage and secrete enzymes that digest the phage. C. modify the attachment sites for the phages so that new infections cannot take place. D. recognize proteins on the surface of the phage and secrete proteins that block the binding of the phage.

D. Recognize proteins on the surface of the phage and secrete proteins that block the binding of the phage