Question 1

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. 
A) Viruses that lead to cancer formation are called oncogenic viruses.
B) The most common viral causes of tumors are certain DNA viruses such as hepatitis B virus.
C) Some viruses carry an oncogene-infection with these viruses interferes with the host cell's own growth-control mechanisms.
D) The majority of tumors are caused by oncogenic viruses but some may be caused by mutations in host genes that regulate cell growth.
E) 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.

Accepted Answer

The statement "The majority of tumors are caused by oncogenic viruses but some may be caused by mutations in host genes that regulate cell growth" is false. In reality, the majority of tumors are not caused by oncogenic viruses, but rather by mutations in host genes that regulate cell growth. While viruses can be a contributing factor, they are not the primary driver of tumor formation.

Question 2

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
A) an RNA virus.
B) a DNA virus.
C) a protein virus.
D) resistant to proteases.
E) an opportunist.

Accepted Answer

Since the contents of tube 2, which were exposed to RNase and protease, were degraded, it indicates that the virus in that tube was RNA-based. The lack of degradation in tube 1 (protease only) suggests that the virus in that tube may have had a protein coat protecting it. The lack of degradation in tube 3 (protease and DNase) suggests that the virus in that tube may have had a DNA genome. Therefore, the best choice is A, an RNA virus.

Question 3

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 friend wonders whether the same type of virus can cause both an acute and a persistent infection? You answer
A) Yes-the initial infection might be acute but the virus can later become latent by becoming integrated into the host cell genome. 
B) No-a virus causes either an acute infection or a persistent infection, but never both. 
C) No-if the initial infection is acute, the virus would have to mutate in the host before being able to cause a persistent infection.
D) Yes-acute and persistent infections are really the same thing except that people with persistent infections recover more quickly than those with acute infections.
E) Yes-acute and persistent infections are really the same thing except that people with acute infections recover more quickly than those with persistent infections.

Accepted Answer

Some viruses, like hepatitis B, can cause an acute infection initially and then become integrated into the host cell genome, causing a persistent infection. This means the same virus can cause both types of infections.

Question 4

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.
-The signs and symptoms of cholera are caused by cholera toxin that is synthesized and secreted by the bacteria. The toxin causes chloride and other electrolytes to leave the intestinal cells. Water follows the electrolytes, resulting in an outpouring of water into the intestinal lumen. The gene for cholera toxin is a bacteriophage gene. This situation is an example of ________.
A) lysogenic conversion
B) DNA-mediated transformation
C) mutation
D) vertical gene transfer
E) indirect selection

Accepted Answer

Lysogenic conversion occurs when a bacteriophage integrates its genome into the host bacterium's genome, leading to the expression of new genes in the host cell. In this case, the gene for cholera toxin is carried by a bacteriophage and is integrated into the V. cholerae genome, leading to the expression of the toxin and the symptoms of cholera.

Question 5

In order to treat cholera, antiviral medication must be given to get rid of the bacteriophage that carries the cholera toxin gene.

Accepted Answer

Cholera is caused by the bacterium Vibrio cholerae, not a virus or bacteriophage. Antibiotics are typically used to treat cholera by killing the V. cholerae bacteria. Additionally, oral rehydration therapy is crucial to prevent dehydration caused by cholera's severe diarrhea and vomiting.

Question 6

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.
-To give more information on virus replication strategies, you explain to your friend the difference between a DNA virus and a RNA virus in terms of replication. You tell him that
A) RNA virus replication always requires a virally encoded RNA polymerase that is an RNA-dependent RNA polymerase; this enzyme uses an RNA template to synthesize a new strand of RNA. DNA viruses use DNA-dependent DNA polymerase in replication.
B) RNA virus replication always requires a virally encoded DNA polymerase, that is an RNA-dependent DNA polymerase; this enzyme uses a DNA template to synthesize a new strand of RNA. DNA viruses use DNA-dependent DNA polymerase in replication.
C) RNA viruses always encode an enzyme called reverse transcriptase, which is an RNA-dependent DNA polymerase that synthesizes DNA from an RNA template. DNA viruses use DNA-dependent RNA polymerase in replication.
D) DNA viruses replicate their genome by means of an RNA-dependent DNA polymerase that synthesizes DNA from an RNA template. RNA viruses replicate their genome by means of a virally encoded replisome.
E) DNA viruses must always first enzymatically degrade one DNA strand before they are able to replicate the remaining strand using the enzyme DNA-dependent RNA polymerase. RNA viruses are single-stranded, so can replicate their genome directly.

Accepted Answer

RNA viruses require an RNA-dependent RNA polymerase in replication, while DNA viruses use DNA-dependent DNA polymerase in replication.

Question 7

Please select the True statement regarding bacteriophage life cycles.
A) Temperate phages lyse their host cells, whereas lytic phages either lyse their host or integrate their DNA into the host cell's genome.
B) Lytic phages lyse their host cells, whereas temperate phages either lyse their host or integrate their DNA into the host cell's genome.
C) In the bacteriophage life cycle, the entire virus enters the host bacterial cell through a hole in the cell wall.
D) Phage particles seek out their bacterial hosts by means of chemotaxis and then attach to random receptors on the host's cell wall.
E) The burst size is the number of bacterial cells that are lysed as a result of being infected by a bacteriophage such as T4.

Accepted Answer

Lytic phages typically follow a lytic life cycle, where they infect the host cell, replicate, and then lyse the host cell to release new virions. Temperate phages, on the other hand, can follow either a lytic or lysogenic life cycle. In the lysogenic cycle, the phage DNA integrates into the host genome and replicates along with it, without causing lysis of the host cell.

Question 8

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
A) 1, 2, and 4
B) 2 and 3
C) 1, 4, and 5
D) 2 only
E) 1 only

Accepted Answer

Bacteriophages must be able to inject their DNA into the host cell to initiate infection. The other options are not requirements for all bacteriophages.

Question 9

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:
A) exocytosis OR fusion
B) endocytosis OR fusion
C) fusion OR phagocytosis
D) endocytosis OR budding
E) budding OR fusion

Accepted Answer

Animal viruses can enter a host cell through endocytosis, which is the process of the cell engulfing the virus, or through fusion, which is the merging of the viral envelope with the host cell membrane. Therefore, option B is the best choice as it includes both mechanisms.

Question 10

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
B) Phospholipid bilayer with host-derived proteins.
C) Phospholipid bilayer studded with both virus- and host-derived proteins.
D) Protein layer with host-derived spikes.
E) Phospholipid monolayer studded with virus- and host-derived proteins.

Accepted Answer

The viral envelope is composed of a phospholipid bilayer studded with both virus- and host-derived proteins. The virally encoded protein spikes insert into specific regions of the host cell's membrane to acquire this envelope.

Question 11

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

Accepted Answer

All of the answer choices are correct. Zoonotic viruses have complex transmission routes involving different host organisms and vector organisms. The vector organisms may have multiple stages in their life cycles that can carry the virus, and the virus may be able to reside in multiple host organisms, making it challenging to control and eradicate the disease. Additionally, driving the vector organism to extinction is not a viable solution, as it can disrupt the ecosystem and lead to unintended consequences. Hence, eradicating a zoonotic disease is virtually impossible.

Question 12

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.
-The phage from which the cholera toxin gene originates is a ________ phage.
A) filamentous
B) lytic
C) temperate
D) Gram-positive
E) double-stranded RNA

Accepted Answer

The phage from which the cholera toxin gene originates is a temperate phage, as it integrates into the host bacterium's genome and can induce lysogenic conversion.

Question 13

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 wonders whether hepatitis B is really a problematic disease. He says that the job of your immune system is to get rid of viruses and virus-infected cells. You tell him that hepatitis B causes an infection in which the causative agent remains in the body for years or even a lifetime, often without causing symptoms of disease. This type of infection is characterized by the continuous low-level production of viral particles and is called a(n) ________ infection.
A) persistent only
B) persistent AND latent
C) chronic only
D) latent only
E) persistent AND chronic

Accepted Answer

Hepatitis B infection is characterized by the continuous low-level production of viral particles and can persist in the body for years or even a lifetime, often without causing symptoms of disease. This type of infection is both persistent and chronic, as the virus continuously replicates in the liver, leading to inflammation and potential liver damage over time. The immune system may not be able to fully eliminate the virus or prevent its ongoing replication, making vaccination a crucial preventative measure.

Question 14

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

Accepted Answer

A lysogen is a bacterium that carries phage DNA (a prophage) integrated into its genome. This occurs when a temperate phage infects a bacterial cell and integrates its DNA into the host's DNA, replicating along with it. The host bacterium is referred to as a lysogen because it is not immediately lysed by the phage as in a lytic cycle.

Quiz 13: Viruses, Viroids, and Prions

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

In order to treat cholera, antiviral medication must be given to get rid of the bacteriophage that carries the cholera toxin gene.

Please select the True statement regarding bacteriophage life cycles.

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

Why is it virtually impossible to eradicate a disease caused by a zoonotic virus?

A lysogen is