43 Questions
What is the main function of a virus particle?
To deliver its DNA or RNA into the host cell
What is the role of the nucleoprotein in a virus?
To assist in the replication of the virus
What is the significance of viruses being unable to generate energy?
It makes them dependent on host cell machinery for replication
What is the term used for a complete virus particle?
Virion
How are viruses classified based on their genome?
By their RNA or DNA genome
What does it mean for viruses to be viewed as mobile genetic elements?
They can insert their DNA into host genome
Which basic patterns does self-assembly of virus capsids follow?
Helical and icosahedral symmetry
What type of viruses exhibit a fringe of glycoprotein spikes or knobs, also called peplomers?
Enveloped viruses
Which morphology is characteristic of the nucleocapsids of many 'spherical' viruses?
Icosahedral
What does the genome of a virus consist of?
DNA or RNA
What is the genomic RNA strand called in orientation if it can serve as mRNA?
Sense (positive sense, plus sense)
What are the parameters for classification of viruses?
Pathogenicity, ecological, physicochemical, genome composition
Based on pathogenicity, how are viruses affecting the same tissue grouped together?
Respiratory tract, gastrointestinal tract, nervous system, genitourinary system
"Arboviruses" are viruses transmitted by:
Blood sucking arthropods and vertebrate hosts
"Roboviruses" are defined in the text as viruses with:
"Rodent reservoirs"
"Nucleocapsids" consist of a helical array of capsid proteins wrapped around a helical filament of:
"Nucleic acid"
"Monopartite genome" refers to a genome that occupies:
"One nucleic acid molecule"
"Families" and "genera" are terms used for classifying viruses based on:
Morphology, genome structure, and replication
Which virus family does not have an envelope?
Adenoviridae
Which virus family has a complex capsid symmetry?
Herpesviridae
Which virus family has a single-stranded DNA genome?
Papoviridae
Which RNA virus family has an icosahedral capsid symmetry?
Togaviridae
Which DNA virus family has an enveloped capsid?
Papoviridae
Which DNA virus family has a complex capsid symmetry?
Herpesviridae
Which RNA virus family has a single-stranded positive-sense genome?
Astroviridae
Which viruses are designated by a number for subspecies?
Parvoviruses
What is the nucleic acid type of Picornaviruses?
SS(+) RNA
What is the capsid symmetry of Caliciviruses?
Icosahedral
Which statement accurately describes the role of the viral genome in a complete virus particle?
It is enclosed within the capsid and interacts with the host cell machinery for replication.
What distinguishes viruses from other microorganisms in terms of energy generation?
Viruses rely solely on the host cell's biochemical machinery for energy generation.
What is the primary function of the nucleocapsid in a virus?
Delivers the viral genome into the host cell.
Why are viruses considered as mobile genetic elements?
Viruses can integrate their genetic material into a host cell's genome.
What characteristic distinguishes virions from host cell organelles?
The presence of a RNA or DNA genome
Which virus family is characterized by a simplex dsDNA and an icosahedral capsid symmetry?
Papoviridae
What is the family name for a virus with a single-stranded negative-sense RNA and a helical capsid symmetry?
Rhabdoviridae
Which virus family has a genome consisting of single-stranded positive-sense RNA and is enveloped with an icosahedral capsid symmetry?
Coronaviridae
Which virus family is characterized by a single-stranded positive-sense RNA and a capsid symmetry of unknown type?
Flaviviridae
What is the family name for a virus with a double-stranded DNA genome and an icosahedral capsid symmetry?
Herpesviridae
What is the term used for the nucleocapsids of many filamentous and pleomorphic viruses?
Nucleicapsids
Which criteria are NOT used for the classification and nomenclature of viruses as mentioned in the text?
Pathogenicity
Which type of genome necessitates different replication strategies for a virus?
Multipartite genome
What is the term for the genomic RNA strand of single-stranded RNA viruses in orientation if it can serve as mRNA?
Positive sense
Which feature is NOT used for the classification of viruses?
Genetic origin
Study Notes
Virus Structure and Function
- The main function of a virus particle is to infect a host cell and replicate itself.
- The nucleoprotein plays a crucial role in a virus, as it protects the genetic material and helps in the replication process.
Virus Classification
- Viruses are classified based on their genome, which can be single-stranded RNA, double-stranded DNA, or single-stranded DNA.
- The parameters for classification of viruses include morphology, replication strategy, and genome type.
Virus Morphology
- Icosahedral capsid symmetry is characteristic of many RNA viruses.
- Helical symmetry is characteristic of many filamentous and pleomorphic viruses.
- The nucleocapsids of many 'spherical' viruses have a characteristic "spherical" morphology.
Genome and Replication
- The genome of a virus consists of genetic material, which can be DNA or RNA.
- The genomic RNA strand of single-stranded RNA viruses is called "positive-sense" if it can serve as mRNA.
- Viruses are unable to generate energy and rely on the host cell's energy sources.
Terms and Definitions
- A complete virus particle is called a "virion".
- "Arboviruses" are viruses transmitted by arthropods.
- "Roboviruses" are viruses with a robot-like capsid structure.
- "Nucleocapsids" consist of a helical array of capsid proteins wrapped around a helical filament of genetic material.
- "Monopartite genome" refers to a genome that occupies a single segment of genetic material.
- "Families" and "genera" are terms used for classifying viruses based on their evolutionary relationships.
Virus Families
- The herpesvirus family does not have an envelope.
- The adenovirus family has a complex capsid symmetry.
- The parvovirus family has a single-stranded DNA genome.
- The picornavirus family has an icosahedral capsid symmetry and a single-stranded positive-sense RNA genome.
- The herpesvirus family has an enveloped capsid and a double-stranded DNA genome.
Other
- Viruses are considered "mobile genetic elements" because they can move genetic material between hosts.
- The primary function of the nucleocapsid is to protect the genetic material and facilitate replication.
- Viruses are distinguished from other microorganisms by their inability to generate energy.
Test your knowledge on the structure and classification of viruses, including their genetic composition and host interaction. Learn about the unique properties of viruses and their behavior outside the host cell.
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