Virology L3

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What is the smallest known virus?

Pox virus

Ebola Virus

Porcine circovirus type 1 (correct)

Rotavirus

Which virus is the largest in size?

Rotavirus

Pox virus (correct)

Rabies virus

Tobacco mosaic virus

What does the term “pleomorphism” refer to in virology?

The ability of a virus to infect multiple species

The process by which viruses cause disease

The replication mechanism of viruses

The ability of a virus to alter its shape or size (correct)

Which virus has a filament-shaped structure?

Ebola virus Signup and view all the answers

What is the characteristic shape of the rabies virus?

Bullet-shaped Signup and view all the answers

Which virus is rod-shaped?

Tobacco mosaic virus Signup and view all the answers

What is the shape of a bacteriophage?

Tadpole-shaped Signup and view all the answers

How is the shape of poxvirus described?

Brick-shaped Signup and view all the answers

List the common methods used to determine the morphology of viruses.

Electron microscopy, Cryo-EM, X-ray crystallographic method and nuclear magnetic resonance (NMR) Signup and view all the answers

What is the protein coat encasing a virus’s nucleic acid called?

Capsid Signup and view all the answers

What are capsomeres?

The basic subunits of the capsid in a virus Signup and view all the answers

Describe the layers of your “winter jacket” in the context of the morphology of a virus

The envelope is the most outer layer of the virus, then the capsid, and finally the nucleic acid that’s encased within the capsid Signup and view all the answers

Which virus is unique for having a double layered capsid?

Reoviruses Signup and view all the answers

Which of the following techniques is NOT commonly used to determine virus morphology

Gram staining Signup and view all the answers

What is the main function of the capsid of a virus?

Encapsulate and protect the viral nucleic acid/genome Signup and view all the answers

What does the term nucleocapsid refer to in virology?

The capsid and virus nucleic acid (DNA or RNA) combined Signup and view all the answers

How do viruses acquire an envelope?

By budding through the host cell membrane Signup and view all the answers

Which type of capsid symmetry is found in all animal viruses with helical nucleocapsids?

Helical Signup and view all the answers

What is unique about helical nucleocapsids in plant viruses?

They are always naked, without a lipid envelope Signup and view all the answers

What are the two types of capsomeres in icosahedral capsid symmetry?

Pentagonal capsomeres (pentons) and hexagonal capsomeres (hexons) Signup and view all the answers

How many pentons are always present in an icosahedral capsid?

12 Signup and view all the answers

What is the formula to calculate the triangulation number (T-number) of an icosahedral capsid?

T = h^2 + h x k + k^2 Signup and view all the answers

What is the T-number of the simplest icosahedral virus, such as parvovirus?

T = 1 Signup and view all the answers

What are the T-numbers of the inner and outer capsid layers in Reoviridae?

Inner: T=2, Outer: T=13 Signup and view all the answers

What characterizes complex capsid symmetry in viruses?

Visions with several parts, each with separate shapes and symmetries Signup and view all the answers

Which virus is an example of complex symmetry?

Poxvirus Signup and view all the answers

What type of virus typically contains complicated structures and exhibits complex symmetry?

Bacteriophages Signup and view all the answers

How does the viral capsid protect the nucleic acid of a virus?

By providing a barrier against enzymes, chemicals, and environmental conditions like pH and temperature Signup and view all the answers

The viral capsid contributes to which aspect of the virus?

The structural symmetry of the virus particle Signup and view all the answers

Which function of the viral capsid is critical for the virus to attach to a host cell?

Facilitating receptor attachment through specific proteins on the capsid Signup and view all the answers

What does the viral capsid facilitate during the packaging process?

Recognition and packaging of the viral genome Signup and view all the answers

Why are antigenic sites on the viral capsid important?

They determine the antigenicity of the virus Signup and view all the answers

Which of the following is NOT a function of the viral capsid?

Synthesizing viral proteins in the host cell Signup and view all the answers

Which cellular membranes can contribute to the formation of a viral envelope?

Cytoplasmic membrane, Golgi membrane, or nucleus membrane Signup and view all the answers

What are the two types of proteins primarily found in the viral envelope?

Glycoproteins and matrix proteins Signup and view all the answers

What is the primary function of glycoproteins in the viral envelope?

Perform receptor binding, hemagglutination, antigenicity, and membrane fusion Signup and view all the answers

What is the role of channel proteins in the viral envelope?

Form a protein-lined channel that alters membrane permeability Signup and view all the answers

Which type of protein in the viral envelope plays a crucial role in virus assembly?

Matrix protein Signup and view all the answers

What is the function of matrix proteins in the viral envelope?

Stabilize the lipid envelope and link the nucleocapsid to the envelope Signup and view all the answers

How do glycoproteins in the viral envelope contribute to antigenicity?

By being recognized as antigens by the host immune system Signup and view all the answers

What role does the matrix protein play at the plasma membrane during viral assembly

It mediates the encapsulation of the RNA-nucleoprotein cores into the membrane envelope Signup and view all the answers

Which of the following is not a mechanism of genetic diversity of viruses?

Conjugation Signup and view all the answers

What condition is required to maintain the lipid bilayer in the envelope of a virus?

Aqueous or moist environments Signup and view all the answers

Why are enveloped viruses more susceptible to sterilization compared to non-enveloped viruses?

Their lipid bilayer can be dissolved by lipid solvents Signup and view all the answers

Which of the following substances can inactivate enveloped viruses by dissolving their lipid membrane?

Ether and chloroform Signup and view all the answers

What environmental factors can inactivate the lipid bilayer of enveloped viruses?

Desiccation, heat and alteration of pH Signup and view all the answers

What is antigenic drift in viruses?

Mutation that results in minor changes to the virus Signup and view all the answers

What is one possible outcome of antigenic drift in viruses?

Viruses become resistant to antiviral drugs Signup and view all the answers

What is antigenic shift in viruses?

Reassortment of genetic material in viruses with segmented genomes Signup and view all the answers

What are the two mechanisms of antigenic shift?

Recombination and reassortment Signup and view all the answers

What is the primary difference between recombination and reassortment in antigenic shift?

Recombination occurs within a single virus, while reassortment involves two viruses with segmented genomes Signup and view all the answers

Which mechanism of genetic diversity is most important in viruses with segmented genomes?

Reassortment Signup and view all the answers

Which viral enzyme enables a retrovirus to integrate its genetic material into the host's DNA?

Retroviral integrase Signup and view all the answers

What is the function of reverse transcriptase in viral infection?

It generates complementary DNA (cDNA) from an RNA template Signup and view all the answers

What role does nucleic acid polymerase play in viruses?

Facilitates viral genome replication Signup and view all the answers

Which type of viral protein is NOT typically present in extracellular virions?

Nonstructural proteins Signup and view all the answers

Which enzyme is critical for retroviruses like HIV to successfully incorporate their genetic material into the host's DNA?