Viral Envelope Glycoproteins and Capsid Assembly Quiz

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Questions and Answers

How are envelope glycoproteins synthesized and inserted into the plasma membrane?

Envelope glycoproteins have large glycosylated ectodomains, hydrophobic transmembrane anchor domains, and short internal tails, synthesized in the ER and inserted into the plasma membrane via standard export pathways.

What is the role of glycosylation in preventing viral aggregation?

Glycosylation of viral surfaces prevents dehydration and reduces protein-protein interactions to prevent viral aggregation.

How do capsid assembly and packaging signals contribute to genome incorporation into virions?

Capsid assembly varies based on size, shape, and genomic composition and may involve scaffolding proteins and concatemer formation to fill the genome. Packaging signals on viral genomes interact with capsid proteins to direct the specificity of genome incorporation into virions.

What are the six categories of organisms that can serve as hosts for viruses, as mentioned in the text?

<ol> <li>bacteria, archaea, lower eukaryotes (fungi, protozoa, algae), plants, invertebrates, vertebrates (including humans)</li> </ol> Signup and view all the answers

What are the criteria used to group virus species into genera?

<ol> <li>Genome organization and size 2) Structure of the virion 3) Replication strategies 4) Related by evolution but may have divergences in nucleotide and amino acid sequences 5) Infect different organisms or cells/tissues within an organism</li> </ol> Signup and view all the answers

How are bacteriophages named?

They include the name of the host bacterial genus and an arbitrary number, e.g. Bacillus phage SP01 Signup and view all the answers

What distinguishes satellite viruses from satellite nucleic acids?

Satellite viruses only encode their own capsid proteins, while satellite nucleic acids replicate only in the presence of a helper virus and either encode no proteins, or encode only non-capsid proteins. Their genomes are encapsidated by the helper virus capsid. Signup and view all the answers

What are the components of a viral envelope and how do they form?

The components of a viral envelope include lipid bilayers with similar protein composition as the cellular membrane, viral glycoproteins embedded in the lipid bilayer, and a variety of shapes that are not always symmetrical. The envelopes form through the process of budding at the cell membrane, where viral glycoproteins are inserted into the cell membrane and the nucleocapsid is wrapped in a membrane into which viral glycoproteins have been inserted. Signup and view all the answers

How does the lipid content of the lipid bilayer reflect the composition of the membrane it was derived from? Provide an example.

The lipid content of the lipid bilayer reflects the composition of the membrane it was derived from. For example, the influenza virus buds from the cell surface and has cholesterol and phospholipid in proportions that are similar to the plasma membrane. By analyzing the lipids, scientists can determine where the virus budded from. Signup and view all the answers

What is the role of glycoproteins (spikes) in forming the viral envelope?

Glycoproteins (spikes) are inserted into the lipid membrane to form the viral envelope. These glycoproteins play a crucial role in the interactions between the viral envelope and the host cell, as well as in the recognition and attachment to the host cell during the infection process. Signup and view all the answers

Study Notes

Viral Envelope Glycoproteins and Capsid Assembly

Envelope glycoproteins have large glycosylated ectodomains, hydrophobic transmembrane anchor domains, and short internal tails, synthesized in the ER and inserted into the plasma membrane via standard export pathways.
There are two types of integral membrane proteins, Type I and Type II, each with different orientations and signal sequences for membrane insertion.
Hemagglutinin (HA) from influenza virus has an ectodomain for cell receptor binding, a transmembrane anchor domain, and a cytoplasmic tail.
Glycosylation of viral surfaces prevents dehydration and reduces protein-protein interactions to prevent viral aggregation.
Capsid assembly varies based on size, shape, and genomic composition and may involve scaffolding proteins and concatemer formation to fill the genome.
Packaging signals on viral genomes interact with capsid proteins to direct the specificity of genome incorporation into virions.
Core proteins associated with the viral genome inside the capsid neutralize negative charges on DNA and condense the viral DNA for optimal packaging, resembling chromatin.
Interactions between viral proteins drive the formation of viral envelopes by budding, involving membrane curvature and localized protein aggregates.
Budding can be driven by interactions between envelope glycoproteins, matrix proteins, or nucleocapsids, and may involve different mechanisms depending on the virus type.
Virions can release their genomes through proteolytic cleavage of capsid proteins, unspooling of the genome, or interaction with cytoplasmic components.
Virions are energetically metastable and can easily dissociate with the right trigger, such as binding to a receptor or protein on the cell surface or in the cytoplasm.
Virus classification is based on molecular architecture, genetic relatedness, and host organism, with criteria including nucleic acid genome type, strandedness, topology, capsid symmetry, and presence or absence of an envelope. Comparing genomic and amino acid sequences helps determine genetic relatedness.

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Description

Test your knowledge of viral envelope glycoproteins and capsid assembly with this quiz. Explore topics such as glycoprotein structure, viral genome packaging, capsid assembly, and virion release mechanisms. Sharpen your understanding of viral architecture and classification based on genetic relatedness and host organism.