Deck 2: Virus Structure and Assembly

Question 1

Which of the following h and k values will produce a triangulation number of 13?

A)1 and 1
B)1 and 2
C)1 and 3
D)2 and 3
E)2 and 4

Answer 1

C

Question 2

A very common structure for bacteriophage particles is which of the following?

A)an icosahedral head and an envelope
B)a naked icosahedral head
C)a naked helical tail
D)an icosahedral head with a helical tail
E)a cubic head with a helical tail

Answer 2

D

Question 3

Which of the following is a description of a scaffolding protein?

A)A cellular protein that acts as a chaperone during assembly of a helical capsid.
B)A viral protein that is used on the outside of an icosahedral capsid during assembly.
C)A viral protein used on the inside of an icosahedral capsid during assembly and then removed.
D)A protease that trims the proteins during assembly of an icosahedral capsid.
E)A energy dependent motor used to package the genome into larger icosahedral capsids.

Answer 3

C

Question 4

A Type I membrane protein has which of the following structures?

A)Both the C-terminus and the N-terminus face the inside of the virion.
B)It passes through the viral envelope multiple times.
C)The N-terminus faces outside the virion and the C-terminus faces inside the virion.
D)The N-terminus faces inside the virion and the C-terminus faces outside the virion.
E)The protein lacks a transmembrane domain and is secreted from the infected cell.

Question 5

A packaging sequence is involved in which of the following assembly processes?

A)The assembly of the capsid around the genomic nucleic acid.
B)The correct binding of capsid proteins to each other.
C)The insertion of the viral glycoproteins in the envelope.
D)The acquisition of the envelope by the capsid.
E)The packaging of the matrix proteins into the virion.

Question 6

The nucleocapsid describes the structure that includes the:

A)capsid and the genome
B)capsid and the envelope
C)envelope and the glycoproteins
D)helical capsid and an envelope
E)icosahedral capsid and an envelope

Question 7

A scaffolding protein is important for assembly of an icosahedral capsid…..

A)but does not bind to the viral genome.
B)but does not become part of the final virion.
C)and helps to cut the genome into unit lengths.
D)and binds to the host cell receptor.
E)and assists the virion in exiting the host cell.

Question 8

In a helical nucleocapsid,which of the following MOST affects the LENGTH of the capsid?

A)the $\mu$ (mu)value
B)the $\rho$ (rho)value
C)the size of the genome and the P (pitch)of the helix
D)the size of the capsid protein
E)None of the above.

Question 9

It is possible to get high resolution images of enveloped virus particles using x-ray diffraction.

Question 10

How many copies of the capsid protein would there be in an icosahedral capsid with a Triangulation number of 7?

A)70
B)210
C)280
D)420
E)490

Question 11

Virus particles can be visualized with which of the following?

A)negative staining of virions with electron microscopy
B)negative staining of virions with x-ray diffraction
C)negative staining of thin sections of infected cells with electron microscopy
D)positive staining in cryoelectron microscopy
E)positive staining of infected cells with x-ray diffraction

Question 12

Most viruses that use a spherical shaped capsid arrange their capsid proteins with which of the following symmetries?

A)cubic
B)tetrahedral
C)icosahedral
D)dodecagon
E)helical

Question 13

Depending on the type of virus,which of the following is a function of the virus capsid?

A)To attach to the correct type of host cell.
B)To protect the viral genome from nucleases.
C)To ensure delivery of the genome into the host cell.
D)To protect the viral genome from damage by UV light.
E)All of the above functions are correct.

Question 14

The lipid membrane that surrounds the nucleocapsid of some virus particles is called the:

A)matrix
B)tegument
C)capsid
D)envelope
E)glycoprotein

Question 15

Which of the following describes the number of subunits per turn in a helical capsid?

A)P (pitch)
B) $\mu$ (mu)
C) $\rho$ (rho)
D)Triangulation number
E)symmetry

Question 16

The Jelly Roll $\beta$ barrel is:

A)a structure found in many viral envelope glycoproteins.
B)a structure found in many viral capsid proteins.
C)the structure the viral genome takes inside of a helical capsid.
D)the structure the viral genome takes inside an icosahedral capsid.
E)the structure of many helical capsids as the wrap around the genome.

Question 17

Which of the following is NOT a characteristic of a regular icosahedron?

A)It has 12 vertices of 5-fold symmetry.
B)It has 20 triangular faces.
C)It has 20 sides with 3-fold symmetry.
D)It has 30 edges with 2-fold symmetry
E)It has 6 square faces.

Question 18

The capsid of SV40 contains 360 protein copies.Why is this unusual?

A)There is only 1 kind of protein in this capsid.
B)360 is not the correct number of protein capsids for a T = 6 capsid.
C)Six is not a mathematically allowed triangulation number.
D)The proteins have equivalent interactions.
E)The capsid is not large enough to hold the entire genome.

Question 19

Enveloped virions assemble and acquire their envelope by which of the following mechanisms?

A)The nucleocapsids interact directly with the cytoplasmic tails of the envelope glycoproteins and bud through the cellular membrane.
B)The nucleocapsids interact with the matrix protein,which interact with the cytoplasmic tails of the envelope glycoprotein,and the virion buds through the cellular membrane.
C)The envelope is assembled de novo around the nucleocapsid by cellular enzymes.
D)The virion acquires the envelope after it leaves the host cell from extracellular vesicles.
E)Both a and b are used by viruses.

Question 20

What does the term "quasi-equivalent" mean with respect to the proteins in an icosahedral capsid?

A)If the identical protein is used,it has both 5-fold and 6-fold interactions with the other proteins in the capsid.
B)There are different proteins in the capsid with similiar shapes.
C)They all use the "jelly-roll" protein structure.
D)There can be more than one type of glycoprotein in the envelope.
E)All of the proteins interact in a 5-fold arrangement.

Question 21

Some viruses particles have a rigid capsid surrounding an internal membrane.

Question 22

Viral envelopes often have very different lipid compositions than the cellular membranes that they originate from.

Question 23

Cryoelectron microscopy uses computer reconstruction of images of multiple virions to produce a high resolution image of a virion or capsid.

Question 24

Virions are often described as being energetically "metastable".What does this mean and why is it important for entry and uncoating of the viral genome into the next host cell?