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Virology > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

What is the function of the cap structure on the 5’ end of viral and cellular mRNAs?

a. Protect mRNAs from 5’-exonucleases
b. Allow recognition of 5’-terminal exons of pre-mRNAs made by RNA polymerase II
c. Direct efficient translation of most viral and cellular mRNAs
d. All of the above

A

d. All of the above

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2
Q

Any viral genome must either already resemble or be copied to which other type of nucleic acid before proteins can be produced?

a. messenger RNA (mRNA)
b. ribosomal RNA (rRNA)
c. DNA
d. transfer RNA (tRNA)

A

a. messenger RNA (mRNA)

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3
Q

Which of the following methods is NOT appropriate for measuring the infectivity of a virus particle?

a. Plaque assay
b. Electron microscopy
c. Endpoint dilution assay
d. Transformation assay

A

b. Electron microscopy

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4
Q

How are RNA viruses able to mutate so rapidly?

a. Recombination between homologous RNA molecules
b. Their RNA polymerases don’t have a proof-reading activity
c. All of these
d. Their genomes can undergo genetic reassortment

A

c. All of these

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5
Q

Which of the following processes MUST use the host cell machinery?

a. Transcription (mRNA synthesis)
b. Translation (protein synthesis)
c. Genome replication
d. Assembly of new virus particles

A

b. translation (protein synthesis)

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6
Q

In which subcellular compartment do glycoproteins undergo proteolytic processing?

a. The ER
b. The Golgi
c. Mitochondria
d. Endosomes

A

b. The Golgi

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7
Q

Which of these cellular structures is most commonly used for movement of viral components for assembly?

a. Actin filaments
b. Ribosomes
c. Microtubules
d. Nuclear membranes

A

c. Microtubules

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8
Q

In which subcellular compartment are viral proteins translated?

a. The nucleus
b. The ER
c. The Golgi
d. The cytoplasm

A

d. The cytoplasm

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9
Q

Which property of some proteins allow them to be translocated to the nucleus after translation?

a. A single peptide
b. A nuclear localication signal
c. A DEAD box helicase domain
d. An IRES

A

b. A nuclear localication signal

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10
Q

Like most enveloped viruses, influenza virus assembles where in the cell?

a. In autophagosomes
b. At the plasma membrane
c. In the nucleus
d. In the Golgi

A

b. At the plasma membrane

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11
Q

One of the major surface proteins of influenza virus is the hemagglutinin protein, HA, which is synthesized as a precursor called HA0. What kind of post-translational modifications are essential for its function?

a. Glycosylation
b. Myristoylation
c. Ubiquitination
d. SUMOylation

A

a. Glycosylation

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12
Q

As a viral envelope protein, influenza virus HA typically contains how many transmembrane domains?

a. seven
b. two
c. one
d. four

A

c. one

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13
Q

Influenza virus HA0 undergoes proteolytic processing into mature functional envelope proteins HA1 and HA2 in which subcellular compartment?

a. The ER
b. The cis Golgi
c. The cytoplasm
d. The trans Golgi

A

d. The tran Golgi network

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14
Q

The influenza virus RNA genome replicates in the nucleus yet assembles new virions at the plasma membrane. Which subcellular structures play a role in transport of influenza virus ribonucleoprotein complexes (RNPs)?

a. Actin filaments
b. Microtubules
c. Mitochondria
d. Proteasomes

A

b. Microtubules

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15
Q

Refer to the process by which proteins are inserted into membranes such as the plasma membrane or those of intracellular organelles like the Golgi apparatus:

Where are such proteins translated?

a. Free in the cytoplasm
b. On smooth ER
c. On rough ER
d. In proteasomes

A

c. On rough ER

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16
Q

Refer to the process by which proteins are inserted into membranes such as the plasma membrane or those of intracellular organelles like the Golgi apparatus:

Which of the following is true of the signal peptides that specify translation in this compartment?

a. They are typically located at the N terminus of proteins
b. They are usually 20 amino acids in length with a core of 15 hydrophobic residues
c. They are often removed enzymatically during protein translocation to the nucleus by signal peptidase
d. All of these are ture

A

d. All of these

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17
Q

The process through which an mRNA encoding a protein enters the ER lumen occurs in 5 steps that are listed. Place in the proper order:

What is the first step?

a. The ribosome and signal peptide bind to the translocation channel, which triggers its opening
b. The growing polypeptide chain is transferred through the membrane as translation continues
c. The SRP binds to the signal peptide and the ribosome to pause translation
d. GTP is hydrolyzed and the SRP is released for subsequent recycling
e. The nascent polypeptide-SRP-ribosome complex binds to the SRP receptor in the ER membrane

A

c. The SRP binds to the signal peptide and the ribosome to pause translation

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18
Q

The process through which an mRNA encoding a protein enters the ER lumen occurs in 5 steps that are listed. Place in the proper order:

What is the second step?

a. The ribosome and signal peptide bind to the translocation channel, which triggers its opening
b. The growing polypeptide chain is transferred through the membrane as translation continues
c. The SRP binds to the signal peptide and the ribosome to pause translation
d. GTP is hydrolyzed and the SRP is released for subsequent recycling
e. The nascent polypeptide-SRP-ribosome complex binds to the SRP receptor in the ER membrane

A

e. The nascent polypeptide-SRP-ribosome complex binds to the SRP receptor in the ER membrane

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19
Q

The process through which an mRNA encoding a protein enters the ER lumen occurs in 5 steps that are listed. Place in the proper order:

What is the third step?

a. The ribosome and signal peptide bind to the translocation channel, which triggers its opening
b. The growing polypeptide chain is transferred through the membrane as translation continues
c. The SRP binds to the signal peptide and the ribosome to pause translation
d. GTP is hydrolyzed and the SRP is released for subsequent recycling
e. The nascent polypeptide-SRP-ribosome complex binds to the SRP receptor in the ER membrane

A

d. GTP is hydrolyzed and the SRP is released for subsequent recycling

20
Q

The process through which an mRNA encoding a protein enters the ER lumen occurs in 5 steps that are listed. Place in the proper order:

What is the forth step?

a. The ribosome and signal peptide bind to the translocation channel, which triggers its opening
b. The growing polypeptide chain is transferred through the membrane as translation continues
c. The SRP binds to the signal peptide and the ribosome to pause translation
d. GTP is hydrolyzed and the SRP is released for subsequent recycling
e. The nascent polypeptide-SRP-ribosome complex binds to the SRP receptor in the ER membrane

A

a. The ribosome and signal peptide bind to the translocation channel, which triggers its opening

21
Q

The process through which an mRNA encoding a protein enters the ER lumen occurs in 5 steps that are listed. Place in the proper order:

What is the fifth step?

a. The ribosome and signal peptide bind to the translocation channel, which triggers its opening
b. The growing polypeptide chain is transferred through the membrane as translation continues
c. The SRP binds to the signal peptide and the ribosome to pause translation
d. GTP is hydrolyzed and the SRP is released for subsequent recycling
e. The nascent polypeptide-SRP-ribosome complex binds to the SRP receptor in the ER membrane

A

b. The growing polypeptide chain is transferred through the membrane as translation continues

22
Q

ALL EXCEPT WHICH of the following sugars can be found in a glycosylated protein?

a. Mannose
b. Fructose
c. Glucose
d. N-acetylglucosamine

A

d. Fructose

23
Q

Proper folding of the influenza virus HA0 glycoprotein precursor is essential for its function. Which of these molecular chaperones is involved in its folding?

a. Grp78
b. HSP70
c. GroEL
d. Calnexin

A

d. Calnexin

24
Q

Proteins move from the ER to the Golgi, and within the Golgi subcompartments by budding of transport vesicles from one compartment and docking with the next. In transport of an ER-synthesized protein to the trans golgi network, this process requires which of the following components?

a. Coat protein complex II (COPII), dynein, and microtubules
b. Coat protein complex I (COPI), dynein, and microtubules
c. Coat protein complex II (COPII), kinesin, and microtubules
d. Coat protein complex I (COPI), kinesin, and microtubules

A

a. Coat protein complex II (COPII), dynein, and microtubules

25
Q

During remodeling or processing of N-linked oligosaccharides, for example those found in the influenza virus HA protein, the initial high-mannose core precursor undergoes trimming or removal of mannose. This occurs in which of the following subcompartment of the secretory pathway?

a. The ER
b. The cis-Golgi network
c. The Golgi stacks (cis cisterna, medial cisterna)
d. The trans-Golgi network

A

c. The Golgi stacks (cis cisterna, medial cisterna)

26
Q

What mediates specific recognition of the viral genome during assembly?

a. Packaging signals (sequences) present only on viral genomic DNA/RNA
b. Sequences common to viral and cellular nucleic acids
c. Sequences specific to only cellular nucleic acids signal the ones to be excluded from virions
d. The process is random, there is no specificity

A

a. Packaging signals (sequences) present only on viral genomic DNA/RNA

27
Q

Which of these mechanisms is used for assembly of bacteriophage T4?

a. The “headfull” mechanism for filling empty capsids
b. Assembly at the plasma membrane
c. Assembly of the genome with pre-formed pentamers of 5S structural subunits
d. Chaperone-assisted assembly

A

a. The “headfull” mechanism for filling empty capsids

28
Q

Which of these mechanisms is used for assembly of poliovirus capsids?

a. The “headfull” mechanism for filling empty capsids
b. Assembly at the plasma membrane
c. Assembly of the genome with pre-formed pentamers of 5S structural subunits
d. Chaperone-assisted assembly

A

c. Assembly of the genome with pre-formed pentamers of 5S structural subunits

29
Q

Which of these mechanisms is used for assembly of influenza virus?

a. The “headfull” mechanism for filling empty capsids
b. Assembly at the plasma membrane
c. Assembly of the genome with pre-formed pentamers of 5S structural subunits
d. Chaperone-assisted assembly

A

b. Assembly at the plasma membrane

30
Q

Refer to the assembly of poliovirus particles:

Poliovirus particles contain what kind of nucleic acid genome?

a. Negative strand RNA
b. Positive strand RNA
c. Double stranded RNA
d. Double stranded DNA

A

b. Positive strand RNA

31
Q

Refer to the assembly of poliovirus particles:

Which of the following is true of stable empty capsids?

a. They possess the same conformation as the mature virus particle
b. They are dead-end products
c. Do not require replication of genomic RNA
d. Are not coordinated with genome encapsidation

A

b. They are dead-end products

32
Q

Refer to the assembly of poliovirus particles:

Provirions are comprised of the following components?

a. Genomic RNA
b. 14S capsid pentamers
c. 75S empty capsids
d. a and b

A

d. a and b

33
Q

Refer to the assembly of poliovirus particles:

In the absence of genomic RNA, poliovirus 14S pentamers can self assemble into 75S empty capsids. Are these infectious?

a. yes
b. no

A

b. No

34
Q

Refer to the assembly of poliovirus particles:

Poliovirus assembly initially results in production of a non-infectous provirion that is converted to an infectious virion by a process of maturation. This involves:

a. Cleavage of the viral RNA
b. Cleavage of VP0 to VP2 and VP4
c. Cleavage of VP1
d. Replication of the viral genome

A

b. Cleavage of VP0 to VP2 and VP4

35
Q

Refer to the assembly of poliovirus particles:

This reaction is catalyzed by:

a. A viral protease
b. A cellular protease
c. It catalyzes itself (it is auto-catalytic)
d. It does not require any catalytic activity

A

c. It catalyzes itself (it is auto-catalytic)

36
Q

Refer to the assembly of poliovirus particles:

Do poliovirus virions have a lipid envelope?

a. yes
b. no

A

b. no

37
Q

How do poliovirus particles exit infected cells?

a. By cell lysis
b. By autophagy
c. By budding
d. a and b

A

d. a and b

38
Q

Refer to the assembly of influenza virus particles:

Influenza virus particles contain what kind of nucleic acid genome?

a. Negative strand RNA
b. Positive stranded RNA
c. Double stranded RNA
d. Double stranded DNA

A

a. Negative strand RNA

39
Q

Refer to the assembly of influenza virus particles:

Influenza virus genomic RNA is packaged into ribonucleoprotein complexes (RNPs) by the RNA-binding protein NP. What function do these RNPs serve?

a. Templates for mRNA synthesis
b. Templates for genome replication
c. Binding of M1 matrix protein
d. All of these

A

d. All of these

40
Q

The process of influenza virus assembly occurs in a stepwise fashion. Please place the steps in the proper order:

Which is the first step?

a. Release of the enveloped particle
b. Viral HA, NA, and M2 proteins transported to plasma membrane by the cellular secretory pathway
c. Binding of RNP-M1 by viral nuclear export protein (NEP) and export to the cytoplasm
d. Budding of RNP/HA/NA/M2 through the plasma membrane

A

c. Binding of RNP-M1 by viral nuclear export protein (NEP) and export to the cytoplasm

41
Q

The process of influenza virus assembly occurs in a stepwise fashion. Please place the steps in the proper order:

Which is the second step?

a. Release of the enveloped particle
b. Viral HA, NA, and M2 proteins transported to plasma membrane by the cellular secretory pathway
c. Binding of RNP-M1 by viral nuclear export protein (NEP) and export to the cytoplasm
d. Budding of RNP/HA/NA/M2 through the plasma membrane

A

b. Viral HA, NA, and M2 proteins transported to plasma membrane by the cellular secretory pathway

42
Q

The process of influenza virus assembly occurs in a stepwise fashion. Please place the steps in the proper order:

Which is the third step?

a. Release of the enveloped particle
b. Viral HA, NA, and M2 proteins transported to plasma membrane by the cellular secretory pathway
c. Binding of RNP-M1 by viral nuclear export protein (NEP) and export to the cytoplasm
d. Budding of RNP/HA/NA/M2 through the plasma membrane

A

d. Budding of RNP/HA/NA/M2 through the plasma membrane

43
Q

The process of influenza virus assembly occurs in a stepwise fashion. Please place the steps in the proper order:

Which is the fourth step?

a. Release of the enveloped particle
b. Viral HA, NA, and M2 proteins transported to plasma membrane by the cellular secretory pathway
c. Binding of RNP-M1 by viral nuclear export protein (NEP) and export to the cytoplasm
d. Budding of RNP/HA/NA/M2 through the plasma membrane

A

a. Release of the enveloped particle

44
Q

The influenza virus genome is segmented, which provides additional challenges in ensuring that each segment is represented in the progeny virion. Which model has been recently proposed to account for this?

a. Random packaging
b. A selective mechanism using base-pairing interactions between the viral RNA segments
c. A head-full mechanism

A

b. A selective mechanism using base-pairing interactions between the viral RNA segments

45
Q

What is required for formation of influenza virus particles of normal size and morphology?

a. Interactions between M1,HA, and NA
b. Interactions between M1 and HA alone
c. Interactions between M1 and NA alone
d. Interactions between HA and NA

A

a. Interactions between M1,HA, and NA

Virology (3 decks)

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