Exam 6

Question 1

True or False: Structurally bacteriophages are similar to viruses that infect animals

Answer 1

False. Bacteriophages have a distinct composition and structure

Question 2

A patient diagnosed with German measles may additionally experience what disease? Select all that apply
A. Impetigo
B. Conjuctivitis
C. Rheumatic fever
D. Influenza-like symptoms

Answer 2

B and D

Question 3

The _____ surrounds the capsid of some viruses

Answer 3

Envelope

Question 4

Which of the following cannot be spread via airborne particles
A. Measles
B. Mumps
C. Rubella
D. A and B
E. None of the above

Answer 4

E. Measles, mumps and rubella can all be spread via airborne particles formed while coughing, sneezing, etc.

Question 5

True or False: Someone who had chicken pox as a child is likely to develop shingles while in college, where the median age of college students is 18-22 years old

Answer 5

False. The most common age for shingles reactivation and shingle diagnosis tends to occur in people greater than 60 years of age

Question 6

Which of the following diseases does a linear, double-stranded DNA virus cause?
A. Measles
B. Mumps
C. Rubella
D. B and C
E. None of the above

Answer 6

E. Measles, mumps, and rubella are linear, single-stranded RNA virus

Question 7

While traveling abroad, should you be worried about coming into contact with either the Variola major or Variola minor viruses?

Answer 7

You do not need to worry about coming into contact with either virus. They are both variants of smallpox, which was eradicated in 1977.

Question 8

True or False. Structurally, bacteriophages are distinct from viruses that infect plant or animal cells.

Answer 8

True. Bacteriophages are structurally distinct from viruses that infect plant and animals cells.

Question 9

True or False: You would expect to see a viral envelope on a virus infecting a bacterial cell

Answer 9

False. Not all the viruses have envelopes

Question 10

Described the main underlining differences between the Salk and Sabin polio vaccine

Answer 10

The Salk vaccine was injected and contained an inactivate form of the virus. The Sabin vaccine contained a live weakened form of the virus and was administered orally

Question 11

True or False: Similar to chickenpox, the blisters that appear with Shingles can cover the entire body

Answer 11

False. Unlike chickenpox blisters, which can form anywhere, the blisters associated with shingles are localized and limited to small areas

Question 12

Describe the two basic components of a virus (short answer)

Answer 12

1. Genomic material made up of either DNA or RNA
2. A capsid that contains the DNA or RNA

Question 13

True or False: The viral capsid of HIV is dumbbell shaped and contains ~2,000 copies of the viral protein p24

Answer 13

False. The HIV capsid is conical (cone shaped)

Question 14

Which subtype of Influenza is the most virulent?

Answer 14

Influenza A

Question 15

You go to visit a friend who has chickenpox. While visiting what are two things you will be sure to avoid so you don’t also become infected?

Answer 15

1. You would want to be sure to keep a distance especially if your friend is coughing or sneezing as chickenpox can be transmitted through air-borne droplets (sneezing/coughs).
2. You would also have to be absolutely certain to avoid direct contact with the blisters of an infected individual

Question 16

What small (~30nm) single-stranded, non-enveloped RNA virus causes temporary or permanent paralysis by infiltrating (infecting) motor neurons within the spinal cord, brain stem or motor cortex?

Answer 16

Polio, also known as poliomyelitis

Question 17

The envelope surrounds the _____ of some viruses

Answer 17

Capsid

Question 18

True or False: A patient infected with Rubella is considered infectious one week before and after the appearance of the trademark rash

Answer 18

True

Question 19

By whom and where was the first Polio vaccine developed?

Answer 19

Jonas Salk along with his research team, at the University of Pittsburgh, developed the first polio vaccine in 1955

Question 20

What linear, double-stranded, enveloped DNA virus is the first virus (as of Oct. 26, 1977) to be officially declared eradicated? (short answer)

Answer 20

Smallpox

Question 21

Explain why the flu shot given each year may not be 100% effective at preventing the flu?

Answer 21

You may be exposed to a viral strain that is not included in the making of the vaccine of the flu shot you took. The flu vaccine is made to prevent the previous year’s strain.

Question 22

Rank the following viruses based on their size from largest to smallest: orthomyxovirus, poliovirus, variolavirus

Answer 22

Variolavirus > Orthomyxovirus > Poliovirus

Question 23

Place the following viral life cycle steps in order beginning with viral attachment and provide a description of each step (short answer)

Answer 23

1. Attachment: receptors bind to host proteins on the surface of the cell
2. Entry: virus fuses with the host membrane, enters cell
3. Uncoating: viral capsid disassembles
4. Replication: viral genome makes copies of itself from the “blueprint”
5. Exit: new viruses are made and leave cell
6. New infection: new viruses go on to infect new cells, process restarts.

Question 24

True or False. A patient infected with Rubella is only considered infectious when the trademark rash is visible.

Answer 24

False. A patient infected with Rubella is infectious one week before and one week after the appearance of the rash.

Question 25

Describe the main differences between lytic and temperate phages (short answer)

Answer 25

Lytic bacteriophages will replicate within the host bacteria causing it to rupture. This destroys the host bacterial cell. Temperate phages can survive in a non-replicative state, they do not kill the host cell. They host the phage DNA without risk of cell death.

Question 26

A drug company is trying to develop a new drug that will inhibit the release of newly produced viral particles. Would the drug company target hemagglutin proteins or neuraminidase proteins? Why?

Answer 26

Neuraminidase proteins because they involve the production and release of viral particles from the host cell

Question 27

The HIV surface glycoprotein gp120 binds what host cellular receptor? (multiple choice)

Answer 27

CD4

Question 28

As individual infected with HIV is placed on anti-retroviral medication. Describe how the medication will affect the virus.

Answer 28

Anti-retrovirals interfere with the process of reverse-transcription. Reverse-transcription is how the virus multiples, it makes copies of itself. Once the virus enters the cell and uncoating is complete, the viral enzyme reverse transcriptase acts on the two RNA copies, creating a supporting DNA strand. This is the step the medication will try to stop. By stopping the virus from multiplying, anti-retroviral medications make the immune system strong enough to fight HIV.

Question 29

True or False: You would expect to see a viral envelope on a virus infecting a plant cell

Answer 29

False. The overwhelming majority of animal viruses are enveloped whereas the majority of plant or bacteria-infecting viruses are not

Question 30

Based on the following image, would you expect the viral titer to be high or low? Why? (cloudy)

Answer 30

Low. As turbidity is a function of the number of intact bacterial cells present in the media, the amount of virus contained within the above tube must be low. As the lytic continues more and more bacterial cells will be destroyed, effectively clearing the media.

Question 31

True or False: Viral replication occurs after it attaches and enters the host cell

Answer 31

True. The viral genome is never replicated before attachment and entry

Question 32

True or False: Highly infectious viruses undergo genome replication prior to viral attachment and entry.

Answer 32

False. The viral genome is never replicated before attachment and entry regardless of its level of infectivity.

Question 33

True or False: The viral capsid of HIV is cone shaped and contains ~2,000 copies of the viral protein p24

Answer 33

True

Question 34

What disease is best characterized by painful swelling of the parotid? (short answer)

Answer 34

Mumps. A patient infected with mumps (aka epidemic parotitis) has swelling in the parotid (salivary glands) located in the neck

Question 35

A virus that infects bacteria is called a _____ and contains a _____ -side polygon capsid (fill in the blank)

Answer 35

Bacteriophage 20-sided

Question 36

A person who has neither previously had chickenpox nor been administered the VZV vaccine is exposed to someone with an active VZV (shingles) outbreak and becomes infected. Explain why (or why not) the person will only develop shingles

Answer 36

The now infected individual will develop chicken pox. Shingles is the reactivation of the dormant varicella-zoster virus, therefore someone who is unvaccinated and has never been exposed would develop chickenpox first.

Question 37

The HIV surface glycoprotein gp41 binds what host cellular receptor? (multiple choice)

Answer 37

CXCR4

Question 38

What diseases displays as a secondary characteristic swelling of the testes/ovaries and pancreas? (short answer)

Answer 38

Mumps. They will have primary swelling in the parotid in the neck but will also have swelling in the testes/ovaries and pancreas

Question 39

True or False: Because the genome is contained within an enclosed space, (much like the nucleus of a cell) viruses are classified as eukaryotic

Answer 39

False. Viruses are neither eukaryotic nor prokaryotic

Question 40

Rank the following viruses based on their size from largest to smallest:Paramyxovirus, Poliovirus, Smallpox virus

Answer 40

Smallpox > Paramyxovirus > Poliovirus