Survey of viruses (Ch.13) Flashcards
(39 cards)
What is a virus?
A virus is a tiny infectious agent composed of nucleic acid (DNA or RNA) surrounded by a protein capsid.
What is a virion?
A virion is a complete, infectious viral particle consisting of nucleic acid and a protein coat (capsid), existing outside the host cell.
What is the difference between a virus and a virion?
A virus is the genetic material (nucleic acid) inside a host cell, whereas a virion is the complete viral particle outside the host cell.
What types of genomes can viruses have?
Viruses can have DNA (double-stranded or single-stranded) or RNA (double-stranded or single-stranded) genomes.
How do viral genomes differ from cellular genomes?
Viral genomes can be single-stranded or double-stranded, and they can be RNA or DNA. Cellular genomes are usually double-stranded DNA.
What is a capsid?
A capsid is a protein shell that surrounds and protects the viral genome.
What are capsomeres?
Capsomeres are individual protein subunits that make up the viral capsid.
What is a viral envelope?
A viral envelope is a lipid membrane surrounding some viruses, derived from the host cell membrane.
What is a nucleocapsid?
A nucleocapsid is the combination of the viral genome (nucleic acid) and the capsid.
What makes viral genomes unique?
Viral genomes can vary widely in structure and composition, such as single-stranded RNA (+ or − ssRNA), double-stranded DNA (dsDNA), and others.
How can viral genomes be used by the host cell?
Viral genomes hijack the host’s metabolic machinery, directing it to replicate viral RNA/DNA and synthesize viral proteins.
How do viruses exhibit host specificity?
Viruses are specific to certain host cells because their viral attachment molecules match receptors on the host cell surface.
What is a bacteriophage?
A bacteriophage (or phage) is a virus that specifically infects bacteria.
What are the two main types of viral replication cycles?
The two main cycles are the lytic and lysogenic cycles.
What are the stages of viral replication?
The stages of viral replication are attachment, entry, synthesis, assembly, and release.
What is the difference between a lytic and lysogenic bacteriophage?
In the lytic cycle, the virus replicates and destroys the host cell. In the lysogenic cycle, the viral genome integrates into the host’s DNA and remains dormant.
What is lysis?
Lysis is the process where the host cell is destroyed after the new virions are released.
What is budding in viral replication?
Budding is when enveloped viruses exit the host cell by pinching off from the host’s cell membrane.
What is a persistent infection?
A persistent infection occurs when viruses continue to be released from the host cell over time without destroying the cell.
What is the difference between a prophage and a provirus?
A prophage is a viral genome integrated into a bacterial chromosome during lysogeny, while a provirus is a viral genome integrated into an animal host’s chromosome during latency.
How can viruses cause cancer?
Viruses can cause cancer by integrating into the host’s DNA and disrupting normal cell division, often through oncogenes (mutated genes).
How are viruses cultured in the laboratory?
Viruses must be cultured inside living cells, either in animals, embryonated eggs, or cell cultures.
Are viruses alive?
Outside host cells, viruses are not alive, but inside host cells, they exhibit characteristics of life, like replication.
What is an umbrella term in virology?
An umbrella term in virology refers to general categories like “DNA viruses” or “RNA viruses,” which include various viral families and types.
