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Which of the following is an accurate description of a virion?
A. the nucleic acid of a viral pathogen
the nucleic acid of a viral pathogen: Viral nucleic acid is a component of a virus, but by itself it does not constitute a virion. A complete virion must include both nucleic acid and a protective protein coat.
B. a mature infectious particle of protein and nucleic acid
a mature infectious particle of protein and nucleic acid: A virion is the fully assembled, extracellular, and infectious form of a virus. It consists of viral nucleic acid (DNA or RNA) encased in a protein capsid, and in some cases, an envelope derived from the host cell.
C. a population of infectious particles
a population of infectious particles: This describes multiple virions, but the term virion specifically refers to a single, complete viral particle.
D. the protein portion of a viral particle
the protein portion of a viral particle: The protein portion alone is called the capsid, not a virion. The capsid is necessary for protection and attachment but does not represent the full infectious particle.
E. the nucleic acid of a viral pathogen inside a host cell
Once inside the host cell, the virus exists as genetic material engaging in replication, but this is not considered a virion since it is no longer in its extracellular, infectious state.
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Full Explanation
A. the nucleic acid of a viral pathogen: Viral nucleic acid is a component of a virus, but by itself it does not constitute a virion. A complete virion must include both nucleic acid and a protective protein coat.
B. a mature infectious particle of protein and nucleic acid: A virion is the fully assembled, extracellular, and infectious form of a virus. It consists of viral nucleic acid (DNA or RNA) encased in a protein capsid, and in some cases, an envelope derived from the host cell.
C. a population of infectious particles: This describes multiple virions, but the term virion specifically refers to a single, complete viral particle.
D. the protein portion of a viral particle: The protein portion alone is called the capsid, not a virion. The capsid is necessary for protection and attachment but does not represent the full infectious particle.
E. the nucleic acid of a viral pathogen inside a host cell: Once inside the host cell, the virus exists as genetic material engaging in replication, but this is not considered a virion since it is no longer in its extracellular, infectious state.
Similar Questions
Viruses are classified by all of the following characteristics, except
A. shape
shape: Viruses are classified by their capsid shape, which may be helical, icosahedral, or complex. This structural feature is a key criterion in viral taxonomy.
B. type of nucleic acid
type of nucleic acid: Viral classification depends on whether the genome is DNA or RNA, single-stranded or double-stranded, and positive- or negative-sense.
C. size
size: The physical size of viruses, ranging from about 20 nm to 300 nm, is one of the factors used in classification.
D. ribosome size
ribosome size: Viruses do not contain ribosomes, as they rely on the host cell’s protein synthesis machinery. Therefore, ribosome size is not a characteristic used in viral classification.
Full Explanation
A. shape: Viruses are classified by their capsid shape, which may be helical, icosahedral, or complex. This structural feature is a key criterion in viral taxonomy.
B. type of nucleic acid: Viral classification depends on whether the genome is DNA or RNA, single-stranded or double-stranded, and positive- or negative-sense.
C. size: The physical size of viruses, ranging from about 20 nm to 300 nm, is one of the factors used in classification.
D. ribosome size: Viruses do not contain ribosomes, as they rely on the host cell’s protein synthesis machinery. Therefore, ribosome size is not a characteristic used in viral classification.
What is the correct order for the stages of a lytic replication cycle, from earliest to latest stages?
A. Synthesis
Synthesis: After entry, the viral genome directs the host cell machinery to synthesize viral nucleic acids and proteins. This step comes after attachment and entry, not at the beginning.
B. Assembly
Assembly: Once viral components are synthesized, they are assembled into complete virions. This occurs later in the cycle, just before release.
C. Attachment
Attachment: The first step is the virus binding to specific receptors on the host cell surface, initiating infection. This allows the virus to target a suitable host cell.
D. Entry
Entry: After attachment, the viral nucleic acid or entire virion enters the host cell through mechanisms like endocytosis or membrane fusion. This is the second step.
E. Release
Release: The final stage is when mature virions exit the host cell, often by lysis in bacteriophages or budding in enveloped viruses, enabling them to infect new cells.
Full Explanation
A. Synthesis: After entry, the viral genome directs the host cell machinery to synthesize viral nucleic acids and proteins. This step comes after attachment and entry, not at the beginning.
B. Assembly: Once viral components are synthesized, they are assembled into complete virions. This occurs later in the cycle, just before release.
C. Attachment: The first step is the virus binding to specific receptors on the host cell surface, initiating infection. This allows the virus to target a suitable host cell.
D. Entry: After attachment, the viral nucleic acid or entire virion enters the host cell through mechanisms like endocytosis or membrane fusion. This is the second step.
E. Release: The final stage is when mature virions exit the host cell, often by lysis in bacteriophages or budding in enveloped viruses, enabling them to infect new cells.
A ____________ is a clear zone on a bacterial lawn where cells have been killed by the
A. activity of a bacteriophage.
activity of a bacteriophage: This describes the cause of the clear zone, since bacteriophages infect and lyse bacterial cells, but it is not the correct term used for the zone itself.
B. colony
colony: A colony is a visible cluster of bacterial cells originating from a single progenitor cell, not a clear zone caused by viral lysis.
C. plaque
plaque: A plaque is the clear area formed on a bacterial lawn where bacteriophages have infected and destroyed bacterial cells. It represents viral activity and spread.
D. lawn
lawn: A lawn refers to the uniform layer of bacterial growth on the agar surface, which serves as the background where plaques can be observed.
E. culture
A culture is the overall growth of microorganisms in a medium, not the specific clear zone produced by bacteriophage activity.
Full Explanation
A. activity of a bacteriophage: This describes the cause of the clear zone, since bacteriophages infect and lyse bacterial cells, but it is not the correct term used for the zone itself.
B. colony: A colony is a visible cluster of bacterial cells originating from a single progenitor cell, not a clear zone caused by viral lysis.
C. plaque: A plaque is the clear area formed on a bacterial lawn where bacteriophages have infected and destroyed bacterial cells. It represents viral activity and spread.
D. lawn: A lawn refers to the uniform layer of bacterial growth on the agar surface, which serves as the background where plaques can be observed.
E. culture: A culture is the overall growth of microorganisms in a medium, not the specific clear zone produced by bacteriophage activity.