Microbiology, Ch 13 Nester's 9th

If you had three tubes of flu viruses and you exposed tube 1 to protease, tube 2 to protease and RNase, and tube 3 to protease and DNase, and the contents of tube 2 were be degraded, you would be able to conclude that:

- an RNA virus RNases cleave RNA molecules

A positive (+) strand of RNA: The negative (-) sense strand of RNA:

- can directly act as mRNA - is used to synthesize more (+) strands.

Viruses are commonly referred to by their ______ name.

- disease AND species

A virion is composed of: - protein, either RNA or DNA, and possibly lipid. - protein and either RNA or DNA, but no lipid. - protein, and possibly lipid. - lipid, protein, and either RNA or DNA. - protein and both RNA and DNA, but no lipid.

- protein, either RNA or DNA, and possibly lipid.

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)

Cells infected with animal viruses lyse because: - the release of the virions depletes the cell of energy. - the virus releases enzymes that lyse the cell. - functions necessary for cell survival are not carried out and the cell dies. - the virus RNA and cellular protein interact to kill the cell.

*functions necessary for cell survival are not carried out and the cell dies.

Transduction resulting from a packaging error: Transduction resulting from an error in excision of a prophage:

- Generalized Transduction - Specialized Transduction

Phage that lyses the bacterial host when completing its life cycle: Phage that is able to incorporate its genome into the host chromosome:

- Virulent Phage -Temperate Phage

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.

T/F Generalized transduction involves the transfer of phage genes from one bacterial cell to another.

False

T/F Generalized transduction is so called because specific bacterial genes are transferred during this process.

False

TRUE OR FALSE: Completed filamentous phages are often found in the cytoplasm of infected bacteria.

False

Example of spikes on viruses

H and N on the influenza virus.

Why is it not surprising that AIDS patients frequently suffer a viral-induced tumor?

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

Explain why HIV becomes resistant so quickly when a single drug is used therapeutically.

HIV uses reverse transcriptase to make a cDNA version of its RNA genome. This polymerase is "'sloppy," with a high rate of error and lack of a proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance.

Why are viroids resistant to nucleases? - Viroids have only been identified in plants. Plant nucleases cannot digest RNA. - Nucleases will only digest DNA, not RNA, so viroids are protected. - Having a circular RNA "genome," with no protein shell, they are resistant to the protein-degrading activities of nucleases. - Viroids are composed of single stranded RNA; nucleases only act on double-stranded molecules. - Having a circular RNA "genome," they are resistant to most exonucleases (that digest the free ends of RNA or DNA).

Having a circular RNA "genome," they are resistant to the digestion of most exonucleases (that nibble/digest the free ends of RNA or DNA).

The replicative form of nucleic acid in filamentous phages is: - dsRNA. - dsDNA. - positive ssDNA. - negative ssDNA. - positive ssRNA.

I said dsDNA (the RF - replicative form) and got it wrong. Fig 13.8 says the filamentous phage has positive ssDNA. If asked again... -but pg341 "This double stranded DNA is referred to as the replicative form (RF)."

Which of the following is NOT true of prions?

Prions that cause spongiform encephalopathies have a different amino acid sequence from PrPc.

What part of the E. coli T4 phage attaches to the host cell receptors?

Protein fibers at the end of the phage tail.

You are graduating from nursing school in three months and have already lined up a new job. However, your employer informs you that before you start your job, it is mandatory for you to be vaccinated against hepatitis B, a double-stranded DNA virus that can cause the disease hepatitis. Your boyfriend, a biology major, wonders why you need to get the vaccine. You aced your microbiology class and you know a lot about both viruses and vaccines, so you understand why getting this vaccination is essential. You give your boyfriend a mini lesson on this by answering a few of his questions. You tell your friend that you are happy to be receiving your vaccination because hepatitis B is associated with hepatocellular carcinoma (liver cancer). Select the FALSE statement regarding viruses and cancer. - Viruses that lead to cancer formation are called oncogenic viruses. - Viruses that insert their genome into the host cell's chromosome may cause changes at the insertion site, converting a proto-oncogene into an oncogene. - Some viruses carry an oncogene—infection with these viruses interferes with the host cell's own growth-control mechanisms. - The majority of tumors are caused by oncogenic viruses but some may be caused by mutations in host genes that regulate cell growth. - The most common viral causes of tumors are certain DNA viruses such as hepatitis B virus.

The majority of tumors are caused by oncogenic viruses but some may be caused by mutations in host genes that regulate cell growth. - pg 351 says "the majority of tumors are not caused by oncogenic viruses, however, but by mutations in host genes that regulate cell growth."

You add an unknown phage to a mixture of F+ and F− cells of E. coli and plate out the bacteria. The bacterial colonies that grow are all F−. How can you explain this phenomenon?

The phage bound to a receptor on the sex pilus, and therefore only infected the F+ cells (leaving the F− cells alone).

Which statement about most phages that contain single-stranded DNA is NOT true? - Their DNA is transformed to dsDNA before replication and transcription occur. - They are extruded from the host cell. - They contain a negative-sense DNA strand. - All of the choices are correct. - None of the choices is correct.

They contain a negative-sense DNA strand - filamentous phases are ssDNA - fig 13.8 shows it being ss(+)DNA

Which statement(s) about cells taken from a tumor is/are true? a) They may be used to grow bacteriophages. b) They divide 50 times and then die AND they may be used to grow bacteriophages. c) They divide 50 times and then die. d) They may be used to grow viruses AND they may be used to grow bacteriophages. e) They may be used to grow viruses.

They may be used to grow viruses.

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

True

T/F - The host range of a virus depends on the presence of host receptor molecules.

True

T/F - Virulent as well as temperate phages can serve as generalized transducing phages.

True

T/F Sometimes a piece of bacterial DNA near the specific site of insertion stays attached to the phage DNA, and a piece of phage DNA remains behind.

True

T/F The lambda phage DNA always integrates into the host DNA in the same specific site.

True

True or false: transduction often involves defective virus

True

true or false: the integration of phage DNA into host DNA occurs in much the same fashion as seen in transformation, transduction, or conjugation.

True

A filamentous phage is incapable of causing a lytic infection.

True - they leave via extrusion

A lysogen is: - a temperate phage that can insert its DNA into the host's DNA. - a bacterium that carries phage DNA (a prophage) integrated into its genome. - an insect that carries virus DNA in its genome. - a bacteriophage that lyses its host as a result of its replication cycle. - a bacteriophage that carries bacterial DNA integrated into its genome.

a bacterium that carries phage DNA (a prophage) integrated into its genome.

During maturation or formation of phage particles:

a few phage heads may surround fragments of host bacterial DNA.

The site at which a virus has infected and subsequently lysed the infected cell, releasing its progeny to infect and lyse surrounding cells, thereby forming a "clear zone," is: - a plaque. - a burst area. - a lyse area. - a dead zone. - a zone of inhibition.

a plague - they count these in plaque assays

Is antigenic shift alone likely to lead to influenza pandemics? a) Perhaps-but it would most likely be a mixture of antigenic shift AND drift that would result in a pandemic strain. b) No-antigenic SHIFT is responsible for changes in the hemagglutinin protein, while antigenic DRIFT is responsible for changes in the neuraminidase protein. You need both to lead to a pandemic strain. c) Yes-ONLY antigenic shift can lead to the large-scale mixing of gene elements required to produce a pandemic flu strain. d) No-ONLY antigenic DRIFT can lead to the large-scale mixing of gene elements required to produce a pandemic flu strain.

a) Perhaps-but it would most likely be a mixture of antigenic shift AND drift that would result in a pandemic strain.

In a quantal assay, animal viruses are quantified by

administering several dilutions of a virus preparation to a number of animals, cells, or chick embryos, then determining the dilution that infected/killed 50% of the group.

Lysogenized cells : are immune to any further infection by any virus. are immune to infection by the same virus. may have new properties. respond to infection with the SOS response. are immune to infection by the same virus AND may have new properties.

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

The changes that occur in virally infected cells are characteristic for a particular virus and are referred to as the: - genotypic expression. - cytology. - cytopathic effect. - symptomatic effect. - phenotypic effect.

cytopathic effect

A mutation in E. coli results in the loss of both restriction endonucleases and modification enzymes. Would you expect any difference in the frequency of gene transfer via transduction FROM Salmonella INTO this E. coli strain? a) Yes-the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading"' viral DNA from the transducing phage. This would lead to higher rates of successful transduction. b) No-transduction efficiency isn't affected by either restriction endonucleases or modification enzymes, so there'd be no effect on the overall rate. c) No-since the Salmonella strain is normal, the rate of production of transducing virus particles would still be the same, resulting in the same frequency of gene transfer. d) Yes-the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading" viral DNA from the transducing phage, AND the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. Together, thesewould lead to higher rates of successful transduction. e) Yes-the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. This would lead to higher rates of successful transduction.

d) Yes-the loss of the restriction endonucleases would leave the recipient E. coli unable to break down "invading" viral DNA from the transducing phage, AND the loss of the modification enzymes would leave the recipient E. coli unable to tag its own DNA as "self," leaving the viral DNA untagged and recognizable as "foreign," and targeted for destruction. Together, thesewould lead to higher rates of successful transduction.

If the infecting phage lacks some critical pieces of DNA necessary for replication, it is called: - incomplete. - defective. - mutated. - vegetative. - carcinogenic.

defective

The common species name of the virus is based on the

diseases the virus causes.

If reasonably pure preparations of virus are available, the number of virus present may be determined by: - light microscopy. - photocolorimetry. - gas chromatography. - spectrophotometry. - electron microscopy.

electron microscopy.

You are graduating from nursing school in three months and have already lined up a new job. However, your employer informs you that before you start your job, it is mandatory for you to be vaccinated against hepatitis B, a double-stranded DNA virus that can cause the disease hepatitis. Your boyfriend, a biology major, wonders why you need to get the vaccine. You aced your microbiology class and you know a lot about both viruses and vaccines, so you understand why getting this vaccination is essential. You give your boyfriend a mini lesson on this by answering a few of his questions. Your boyfriend asks how animal viruses enter a host cell. You tell him that they can use one of two mechanisms: - fusion OR phagocytosis - budding OR fusion - endocytosis OR fusion - endocytosis OR budding - exocytosis OR fusion

endocytosis OR fusion

The phages T4 (lytic) and lambda (temperate) share all of the following characteristics EXCEPT

existing as a prophage

The bacterial viruses that are released by a process termed extrusion are called: - filamentous phages. - lambda viruses. - temperate phages. - helical phages. - lysogenic viruses.

filamentous phages.

The best known chronic infection involves: - herpes. - hepatitis B. - chickenpox. - hepatitis A. - influenza.

hepatitis B

The best-known examples of viruses that cause latent infections are: - measles AND chickenpox. - polio AND herpes. - herpes AND measles. - herpes AND chickenpox. - chickenpox AND polio.

herpes AND chickenpox.

Once inside the host cell, phage DNA

is replicated, may get degraded by bacterial nucleases, and may integrate into the host chromosome.

All of the statements about specialized transduction are correct EXCEPT: - it involves temperate phages. - it involves the random transmission of any gene. - it involves the transfer of a few specific genes. - it involves a defective virus. - it only involves genes near the viral DNA integration site.

it involves the random transmission of any gene. - that is with generalized transduction

The phenomenon responsible for the ability of Corynebacterium diphtherium to produce the virulent toxin responsible for the devastating effects of diphtheria is called: - self-assembly. - phase variation. - matrix conversion. - lysogenic conversion. - prion protein.

lysogenic converstion

Carriers: - have been cured of the infection. - may have a persistent infection. - may be a source of infection. - may have a persistent infection AND may be a source of infection. - usually show symptoms of the disease AND may be a source of infection.

may have a persistent infection AND may be a source of infection.

Prions affect the: - respiratory system. - lymphatic system. - nervous system. - urogenital system. - gastrointestinal tract.

nervous system

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

-probably keep the numbers of bacteria in check AND are active in passing DNA from one bacterium to another

You are a volunteer for Nurses Without Borders and are being sent to a country in Africa. You are excited, because you will have opportunities to go on safari, but you are also somewhat concerned because you have learned from the CDC website that there is currently cholera in the country to which you are going. Patients with cholera experience vomiting and severe diarrhea, producing several liters of liquid stool in a day. This results in signs of dehydration, including sunken eyes, muscle cramps, and in a few cases, convulsions and death. Cholera is caused by the bacterium Vibrio cholerae. You make a list of questions about V. cholerae that you answer with the help of your nursing school study group. All bacteriophages must be able to: 1. inject their DNA into the host cell 2. cause a genetic change in the host cell 3. kill the host cell 4. replicate in the absence of a host 5. exit a host cell by extrusion 1, 4, and 5 1 only 2 only 1, 2, and 4 1, 2 and 3

1 only

The time from absorption to release for T-even phage is about - 1 minute. - 10 minutes. - 30 minutes. - 45 seconds. - 1 day.

30 minutes.

There are ________ major families of DNA-containing viruses that infect vertebrates.

7

Which statement regarding phage replication is TRUE? - Lambda can be a lytic or a temperate phage. - Lambda is a good example of a lytic phage. - When integrated into host DNA, phage DNA is called a virophage. - A lysogen is a virus that has bacterial DNA in it. - A lysogen is a bacterial cell with an integrated prophage.

A lysogen is a bacterial cell with an integrated 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.

Phages that can either replicate and cause cell lysis or can integrate their DNA into the host DNA are called

A temporate phage.

A. A type of horizontal gene transfer occuring when a phage carries a random piece of bacterial DNA acquired when a packaging error occurs during the assembly of phage particles B. Infection that develop slowly and persist for months or years C. Characterized by a lipid bilayer surrounding the nucleocapsid D. The modification of cell properties resulting from expression of phage DNA integrated into a bacterial chromosome E. Infection in which the infectious agent is present but not active

A. Generalized Transdution B. Chronic Infection C. Enveloped Virus D. Lysogenic Conversion E. Latent Infection

A. In virology, the separation of the protein coat from the nucleic acid of the virion B. The structures on the outside of the virion that bind to host cell receptors C. The group of viruses possessed of a single-stranded RNA genome; their enzyme, reverse transcriptase, synthesizes a DNA copy that is then integrated into the host cell chromosome D. The group of fatal neurodegenerative diseases in which brain tissue develops sponge-like holes E. The viral particle in its inert, extracellular form

A. Uncoating B. Spikes (attachment proteins) C. Retroviruses D. Transmissible Spongiform Encephalopathies (TSE's) E. Virion

How do all viruses differ from bacteria? A)Viruses are not composed of cells. B)Viruses do not have any nucleic acid. C)Viruses are obligate intracellular parasites. D)Viruses do not reproduce. E)Viruses are filterable.

A. Viruses are not composed of cells. - viruses are not cells, are not alive, are acellular infectious agents.

A. Protein coat surrounding the nucleic acid of a virus B. Major change in a viral surface antigen that render antibodies made against the previous version ineffective C. Illness characterized by signs and symptoms that develop quickly but last a relatively short time D. Arthropod-borne virus; one of a large group of RNA viruses carried by insects and mites that act as biological vectors E. A virus that infects bacteria; often abbreviated to phage

A. capsid B. Antigenic shift - shift is a MAJOR change whereas drift is a minor change. C. Acute Infection D. Arbovirus E. Bacteriophage

A. The clear area in a monolayer of cells B. The protein that when bound to the operator site prevents transcription C. The latent form of a temperate phage whose DNA has been inserted into the host DNA D. Infectious protein causing a neurodegenerative disease E. A viral infection causing the host cell to lyse

A. plaque B. Repressor C. Prophage D. prion E. Lytic infection

Why is it virtually impossible to eradicate a disease caused by a zoonotic virus? - You would have to drive the vector organism extinct to do so. - Many viruses transmitted in this manner may utilize more than one vector organism. - Many zoonotic viruses may be able to reside in more than one host organism, complicating control measures. - Many vector organisms have multiple stages of their life cycle that can carry a zoonotic virus, which complicates controlling the vector-borne transmission. - All of the answer choices are correct.

All are correct.

Prions - replicate by converting normal host proteins into prion proteins. - responsible for "mad cow disease" can cause a similar disease in humans. - can be transmitted by consumption of dried or cooked food. - that cause Spongiform Encephalopathy have the same amino acids - but different folding properties from PrPc. - all of the above

All of the above.***

Plant viruses may be transmitted by: - humans. - worms. - insects. - contaminated seeds. - All of the choices are correct.

All the choices are correct

Why do animal viruses have envelopes and phages rarely do?

Animal viruses will often use the envelope in order to fuse with the plasma membrane of a new target cell, gaining entry into the cytoplasm.

Which statement concerning viral structure is true? A) The proteins in the envelope are capsomeres. B) Spikes are found on some viruses. They are very consistent in structure and can be used for identification. C) Animal viruses usually contain tail sheaths and spikes. D) All viruses contain an envelope, which is made of lipid, carbohydrate, and protein.

B) Spikes are found on some viruses. They are very consistent in structure and can be used for identification.

2) A feature that may be found in viruses but never in bacteria is A) the ability to pass through 0.22 micrometer pore filters. B) may contain an RNA genome. C) they cannot reproduce themselves outside a host. D) a sensitivity to antibiotics. E) an ability to infect more than one type of host.

B) may contain an RNA genome.

Which of the following statements concerning viruses is true? A) Viruses are usually about the same size as bacteria. B) Viruses possess enzymes for protein synthesis and ATP generation. C) The "host range" for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach. D) Viruses contain both DNA and RNA, and they undergo binary fusion.

C) The "host range" for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.

The nucleocapsid is composed of: - nucleic acid in the ribosome. - DNA or RNA, lipid, and protein. - protein located in the nucleus. - DNA and RNA and protein. - DNA or RNA, and protein.

DNA or RNA, and protein. - a virus will never have DNA AND RNA, it's either or.

Which of the following statements about viruses is FALSE? A) Viruses contain a protein coat. B) Viruses use the anabolic machinery of the cell. C) Viruses have genes. D) Viruses contain DNA or RNA but never both. E) Viruses use their own catabolic enzymes.

E) Viruses use their own catabolic enzymes.

A viroid is a(n) A) complete, infectious virus particle. B) capsid without nucleic acid. C) infectious protein. D) provirus. E) infectious piece of RNA without a capsid.

E) infectious piece of RNA without a capsid. - viroid = RNA only Complete, infectious (extracellular) virus particle = Virion Infectious protein = Prion Provirus = a virus genome that is integrated into the DNA of a host cell. Talking about a bacteriophage? It's called a prophage.

Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why? - Integration, because plasmids are frequently lost during cell division, which could leave a daughter cell without the virus genome. - Plasmids; they're smaller, so they would be easier to replicate by the host cell. - Integrated; the host cell would be less likely to view this DNA as "foreign" on subsequent rounds of replication, and would retain it more easily. - Plasmids; these structures often carry other genes that may give the host cell a selective advantage over cells that don't have them. - Either plasmids or integration because once a virus genome is in a host cell, there is not way for that genome to be removed from the infected cell.

Integration, because plasmids are frequently lost during cell division, which could leave a daughter cell without the virus genome.

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.

Would ID50 and LD50 necessarily be the same for a given virus? Why or why not?

No, because a virus may be highly infectious (very low ID50 value) but only marginally lethal (very high LD50 value), for example the rhinovirus (common cold virus).

An antibiotic is added to a culture of E. coli, resulting in death of the cells. Bacteriophages are then added. Would the phages replicate in the E. coli cells? Why or why not? - No, because the bacteriophages would depend too much on having the active machinery of a living host cell for replication. - Yes, because bacteriophages are capable of reanimating dead cells to force them to produce more virus particles. - No, because dead E. coli cells do not have any receptors on their cell walls to which the bacteriophages can attach for entry into the host cell by fusion. - Yes, because the cellular machinery of the bacteria is most likely still active. The bacteriophages could use that machinery to replicate new virus particles. - No, because entry of the bacteriophages into the target cell is dependent on the cell being alive to conduct endocytosis of the virus.

No, because the bacteriophages would depend too much on having the active machinery of a living host cell for replication.

Would you expect the number of virions to be the same if you measured them by the plaque assay or by counting using the electron microscope? Why? - Yes—both methods measure the total number of virus particles in a solution. - Yes—only fully functioning viruses will be released from a host cell, so the quantified number of virus particles in a plaque assay should be identical to the number of free virus particles counted by electron microscopy. - No—the plaque assay only measures viable virus particles, while the electron microscope cannot distinguish between defective and viable virus. - No—you cannot count virus particles by using a plaque assay. You can only get a relative difference in quantity from one preparation of virus particles to another with this method.

No—the plaque assay only measures viable virus particles, while the electron microscope cannot distinguish between defective and viable virus.

Burst size

Number of phage particles released -for T4 phages, it is around 200

Most enveloped viruses, like hepatitis B, are released by budding, a process whereby the virus acquires its envelope. Before budding occurs, virally encoded protein spikes insert into specific regions of the host cell's membrane. Given this information, which of the following would you tell your friend best describes the structure of the viral envelope? A. Phospholipid bilayer with host-derived proteins. B. Phospholipid bilayer C. Phospholipid bilayer studded with both virus- and host-derived proteins. D. Phospholipid monolayer studded with virus- and host-derived proteins. E. Protein layer with host-derived spikes.

WRONG - B. Phospholipid bilayer - the envelope is a phospholipid bilayer and the spikes are viral-encoded protein. Maybe phospholipid bilayer with both virus and host derived proteins? - found this online: :Phospholipid bilayer derived from host cell membrane. Studded with viral and host cell proteins"

Which does not refer to the shape of a virus? - Helical - Icosahedral - Bacillus - Complex - These are all virus shapes.

bacillus

Attachment of the virus to the host cell (the first step in the viral life cycle) requires:

binding of complementary molecules on the virus and host cell

After entry of the bacteriophage into the host cell, a phage enzyme

breaks the host DNA into fragments.

In addition to lysis, animal viruses may exit the host cell by: - budding. - fusion. - endocytosis. - extrusion. - fission.

budding

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 shape of the virus is determined by its: - envelope. - capsid. - spikes. - nucleic acid. - tail.

capsid - shapes are icosahedral, helical or complex. It's how the capsomeres are put together into the capsid. HInt: bacillus does not refer to the shape of a virus.

Once integrated, phage DNA can remain in the prophage state as long as

certain phage genes are repressed

A virion is a(n): - complete, extracellular virus particle. - pathogenic virus. - subviral particle. - non-enveloped virus particle. - enveloped virus particle.

complete, extracellular virus particle.

Using phages to treat a bacterial infection is an interesting idea because: - of the increasing problem of antibiotic resistance in pathogens. - lysed bacteria pose no threat to a person's health. - of the increasing problem of antibiotic resistance in people. - a single phage can be genetically engineered to infect many different species of bacteria. - a single type of phage can destroy a wide range of strains of the same pathogen.

of the increasing problem of antibiotic resistance in pathogens.

In specialized transduction

only bacterial genes near the site of integration of the phage DNA can be transduced.

Filamentous phages: - only infect E. coli lacking pili. - infect E. coli regardless of the presence of pili. - only infect E. coli that have pili. - do not infect E. coli. - only infect Gram-negative E. coli.

only infect E. coli that have pili.

One group of animal viruses that are able to agglutinate red blood cells are the

orthomyxoviruses.

Spongiform encephalopathy occurs in all of the following EXCEPT - humans. - plants. - sheep. - cattle. - cattle AND sheep.

plants

A difference between plasmids and fragments of DNA that have been transferred between cells is:

plasmids can replicate independently.

Viruses:

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

Phage-encoded enzymes are

produced in a sequential manner AND used to customize the cell for viral production

During attachment of phage to E. coli, the phage: - randomly bumps into the bacteria AND attaches to proteins or carbohydrates on the bacterial surface. - actively seeks out the bacteria AND attaches to proteins or carbohydrates on the bacterial surface. - actively seeks out the bacteria AND attaches to the bacterial DNA. - randomly bumps into the bacteria AND attaches to the bacterial DNA. - randomly bumps into the bacteria AND attaches to the bacterial RNA.

randomly bumps into the bacteria AND attaches to proteins or carbohydrates on the bacterial surface.

The filamentous phages all contain: - single-stranded RNA. - single-stranded DNA. - single-stranded RNA, OR single-stranded DNA - double-stranded RNA. - double-stranded DNA.

single-stranded DNA.

The advantageous genes that can be transferred by transduction are genes for:

sugar fermentation. toxin production. drug resistance.

The integration of phage DNA into the bacterial chromosome occurs because of: - the similarity in enzyme metabolism in the phage and the bacterial cell. - the phage's ability to synthesize enzymes to enter the bacterium AND similar RNA nucleotides in both. - the phage's ability to synthesize an enzyme that integrates its DNA into the host's chromosome. - similarity in RNA nucleotides in both the phage and the bacterial host. - the phage's ability to synthesize enzymes that allow it to enter the bacterium.

the phage's ability to synthesize an enzyme that integrates its DNA into the host's chromosome. - the enzyme integrase

During penetration of E. coli by the T4 phage,: - the tail acts as a "hypodermic needle," injecting the phage DNA into the cell. - the protein fibers digest a hole in the cell wall. - the intact phage enters the host by endocytosis. - lysozyme is used to allow entry of the phage capsid. - the bacterial receptor molecules open a hole through the cell wall.

the tail acts as a "hypodermic needle," injecting the phage DNA into the cell.

A phage that replicates inside the host cell and then lyses its host during its release is a: - dormant phage. - temperate phage. - virulent or lytic phage. - lysogenic phage. - latent phage.

virulent or lytic phage. - ex) T4 lytic phage