Podcast
Questions and Answers
A researcher discovers a novel infectious particle in a plant. Analysis reveals it consists solely of a single-stranded circular RNA molecule. Based on this information, which type of infectious agent is most likely responsible?
A researcher discovers a novel infectious particle in a plant. Analysis reveals it consists solely of a single-stranded circular RNA molecule. Based on this information, which type of infectious agent is most likely responsible?
- Defective Virus
- Pseudo virion
- Prion
- Viroid (correct)
During viral replication, which of the following steps is MOST directly affected by a mutation that disables the host cell's RNA polymerase?
During viral replication, which of the following steps is MOST directly affected by a mutation that disables the host cell's RNA polymerase?
- Replication of the viral genome
- Transcription of early viral genes (correct)
- Uncoating of the viral genome
- Attachment of the virus to the host cell
A virologist is studying a newly discovered virus that contains both DNA and RNA within its capsid. Which of the following known viral agents shares this characteristic?
A virologist is studying a newly discovered virus that contains both DNA and RNA within its capsid. Which of the following known viral agents shares this characteristic?
- Adenovirus
- Mimivirus (correct)
- Bacteriophage
- Retrovirus
A researcher is investigating a virus that can attach to a host cell but cannot replicate without the presence of another virus. This virus replicates its genome and produces its structural proteins only when a second, distinct virus infects the same cell. Which type of viral particle is MOST likely being studied?
A researcher is investigating a virus that can attach to a host cell but cannot replicate without the presence of another virus. This virus replicates its genome and produces its structural proteins only when a second, distinct virus infects the same cell. Which type of viral particle is MOST likely being studied?
Which of the following best describes the primary function of early viral proteins synthesized during the replication cycle of a virus?
Which of the following best describes the primary function of early viral proteins synthesized during the replication cycle of a virus?
If a virus is ONLY capable of binding to a specific receptor on a host cell surface, but fails to penetrate the cell membrane, at which stage is the viral replication cycle being blocked?
If a virus is ONLY capable of binding to a specific receptor on a host cell surface, but fails to penetrate the cell membrane, at which stage is the viral replication cycle being blocked?
Which characteristic distinguishes a virion from a pseudo virion?
Which characteristic distinguishes a virion from a pseudo virion?
Consider a scenario where a virus successfully infects a cell, replicates its genome, and produces viral proteins. However, the newly synthesized viral components fail to assemble into infectious virions. At which stage of the viral replication cycle has the process been disrupted?
Consider a scenario where a virus successfully infects a cell, replicates its genome, and produces viral proteins. However, the newly synthesized viral components fail to assemble into infectious virions. At which stage of the viral replication cycle has the process been disrupted?
Prions are infectious agents known for their unique composition. Which component is exclusively associated with prions?
Prions are infectious agents known for their unique composition. Which component is exclusively associated with prions?
Unlike typical viruses, why aren't viroids able to infect mammalian cells?
Unlike typical viruses, why aren't viroids able to infect mammalian cells?
Flashcards
Virus
Virus
Smallest infectious particle, ranging from 80 to 600 nanometers, containing either DNA or RNA, enclosed in a protein shell (capsid), and requires a host cell for replication because they lack organelles.
Virion
Virion
A complete, infectious virus particle, consisting of nucleic acid (genome) packed into a protein coat (capsid) or a lipid membrane.
Pseudo Virion
Pseudo Virion
A virus-like particle containing non-viral host cell DNA instead of viral DNA; cannot replicate on its own without a helper virus.
Defective Virus
Defective Virus
Signup and view all the flashcards
Viroid
Viroid
Signup and view all the flashcards
Prions
Prions
Signup and view all the flashcards
Mimi Virus
Mimi Virus
Signup and view all the flashcards
Attachment
Attachment
Signup and view all the flashcards
Penetration (Entry)
Penetration (Entry)
Signup and view all the flashcards
Uncoating of Viral Genome
Uncoating of Viral Genome
Signup and view all the flashcards
Study Notes
- Virus particles are the smallest infectious particles, ranging from 80 to 600 nanometers, and can only be seen with powerful microscopes.
- Viruses contain either DNA or RNA, but not both, enclosed in a protein shell (capsid), with or without a lipoprotein envelope.
- Viruses are obligate intracellular parasites, requiring a host cell for replication due to the lack of a nucleus, cytoplasm, mitochondria, or ribosomes.
- Virion refers to a complete virus particle, consisting of a nucleic acid genome packed within a protein coat (capsid) or a lipid membrane.
- Pseudo virions contain non-viral host cell DNA and require a helper virus to replicate, as they cannot replicate on their own.
- Defective viruses contain viral nucleic acid and proteins but need a helper virus for replication and can interfere with the growth of infectious particles, aiding recovery from infection.
- Viroids consist only of a single molecule of circular RNA without a protein coat or lipid envelope, causing plant diseases but not implicated in human diseases.
- Prions are virus particles composed solely of protein, lacking any detectable nucleic acids.
- Mimi viruses contain both DNA and RNA, unlike typical viruses that contain only one type of nucleic acid.
- Adenoviruses, which are non-enveloped DNA viruses, attach to the host cell membrane, penetrate the host cell, and uncoat to release their genome for mRNA and protein synthesis.
- Early proteins, which are viral enzymes for genome replication, and late proteins, such as structural capsid proteins, are synthesized.
- The replicated genetic material and capsid proteins assemble into new virus particles, which are then released from the cell.
Viral Replication Cycle Steps
- Attachment: Virus binds to specific receptors on the host cell’s surface using spike proteins or other surface molecules.
- Penetration (Entry): Virus enters the host cell either by fusion with the cell membrane (enveloped viruses) or by endocytosis (non-enveloped viruses).
- Uncoating of Viral Genome: The viral capsid disassembles, releasing the viral genetic material (DNA or RNA) into the host cell's cytoplasm.
- Early Transcription: Host machinery transcribes early viral genes, producing mRNA for early proteins (enzymes or regulatory proteins).
- Viral mRNA Synthesis: RNA viruses use viral RNA to produce more mRNA; DNA viruses use host machinery to produce mRNA from viral DNA.
- Protein Synthesis: Host ribosomes translate viral mRNA into early proteins for replication, such as enzymes or regulatory proteins.
- Viral Genome Replication: The viral genome (DNA or RNA) is replicated to create multiple copies of the viral genetic material.
- Late Viral mRNA Synthesis: Late viral genes are transcribed to produce mRNA for structural proteins needed for virion assembly.
- Late Protein Synthesis: Host ribosomes translate late mRNA into structural proteins, such as capsid proteins, for new virions.
- Progeny Virion Assembly: Newly replicated viral genomes and structural proteins are assembled into new virions inside the host cell.
- Virion Release from the Cell:
- Non-enveloped viruses lyse (break open) the host cell to release virions.
- Enveloped viruses bud, taking a portion of the host’s membrane to form their envelope.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
