Podcast
Questions and Answers
What is a defining characteristic of viruses?
What is a defining characteristic of viruses?
Which of the following structures is not typically associated with all viruses?
Which of the following structures is not typically associated with all viruses?
What types of nucleic acid can viruses contain?
What types of nucleic acid can viruses contain?
Which of the following viruses is correctly matched with its classification?
Which of the following viruses is correctly matched with its classification?
Signup and view all the answers
Viral tropism refers to what aspect of viruses?
Viral tropism refers to what aspect of viruses?
Signup and view all the answers
Which virus feature describes the arrangement of protein subunits?
Which virus feature describes the arrangement of protein subunits?
Signup and view all the answers
What is viral latency?
What is viral latency?
Signup and view all the answers
Which of the following statements is true regarding virus size?
Which of the following statements is true regarding virus size?
Signup and view all the answers
Which characteristic allows a virus to specifically infect certain types of cells?
Which characteristic allows a virus to specifically infect certain types of cells?
Signup and view all the answers
What is the main reason RNA viruses generally have higher mutation rates than DNA viruses?
What is the main reason RNA viruses generally have higher mutation rates than DNA viruses?
Signup and view all the answers
Which of the following processes is involved in a virus entering a host cell?
Which of the following processes is involved in a virus entering a host cell?
Signup and view all the answers
Which process follows the adsorption of a virus to a host cell?
Which process follows the adsorption of a virus to a host cell?
Signup and view all the answers
What is the term used for the period between viral infection and the production of new virions?
What is the term used for the period between viral infection and the production of new virions?
Signup and view all the answers
Which of the following viruses is classified as a retrovirus?
Which of the following viruses is classified as a retrovirus?
Signup and view all the answers
What type of attachment is critical for the infection process of a virus?
What type of attachment is critical for the infection process of a virus?
Signup and view all the answers
Which type of virus is characterized by a loose outer envelope and positive-sense RNA?
Which type of virus is characterized by a loose outer envelope and positive-sense RNA?
Signup and view all the answers
What occurs during the eclipse phase of viral replication?
What occurs during the eclipse phase of viral replication?
Signup and view all the answers
What type of viral replication results in the death of the host cell?
What type of viral replication results in the death of the host cell?
Signup and view all the answers
Which of the following best describes viral latency?
Which of the following best describes viral latency?
Signup and view all the answers
What is the primary function of mRNA synthesized during viral replication?
What is the primary function of mRNA synthesized during viral replication?
Signup and view all the answers
What distinguishes persistent viral infections from acute infections?
What distinguishes persistent viral infections from acute infections?
Signup and view all the answers
Where does viral assembly typically occur?
Where does viral assembly typically occur?
Signup and view all the answers
What defines the two types of viral proteins produced during the synthesis of viral components?
What defines the two types of viral proteins produced during the synthesis of viral components?
Signup and view all the answers
Which of the following viruses is an example of a persistent infection?
Which of the following viruses is an example of a persistent infection?
Signup and view all the answers
Study Notes
Viruses and their Structure
- Viruses are infectious particles that reproduce by hijacking a host cell's machinery to create more of themselves.
- They are composed of a DNA or RNA genome enclosed in a protein shell called a capsid.
- Some viruses also have an external membrane envelope.
- Viruses come in various shapes, structures, genomes, and infect different hosts.
- They are extremely small, ranging from 10-100 nanometers – about 1/10th the size of bacteria.
- Viruses exclusively replicate within a living host cell, making them obligate intracellular parasites.
Virus Structure and Classification
- Viruses are classified based on their symmetry and nucleic acid type.
-
Symmetry:
- Icosahedral: Viruses with a symmetrical, 20-sided shape (e.g., adenoviruses, polioviruses)
- Filamentous: Long, rod-shaped viruses (e.g., rabies virus, Ebola virus)
- Head-Tail: Complex structures with a head containing the genetic material and a tail for attaching to the host cell (e.g., bacteriophages)
-
Nucleic Acid:
- Viruses can contain either DNA or RNA, but never both.
- DNA viruses include double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA).
- RNA viruses include double-stranded RNA (dsRNA) and single-stranded RNA (ssRNA).
- RNA viruses generally exhibit higher mutation rates than DNA viruses.
Viral Replication and Dissemination
- Viral replication involves a series of steps:
- Adsorption: The virus attaches to specific receptors on the host cell membrane.
- Penetration: The virus enters the host cell through endocytosis, fusion, or translocation.
- Uncoating/Eclipse: The virus's outer membrane and capsid break down, releasing its nucleic acid.
- Transcription: The viral nucleic acid acts as a template for the synthesis of viral mRNA.
- Synthesis of Viral Components: The viral mRNA codes for the production of viral proteins and nucleic acids.
- Assembly: Newly synthesized components are assembled into new viral particles.
- Release: New virus particles are released from the host cell, potentially causing the cell to die (lytic replication) or allowing it to continue living (lysogenic replication).
Viral Persistence and Latency
- Viral Persistence: The virus remains within the host's cells without being eradicated, potentially causing persistent infections (e.g., HIV, Epstein-Barr virus).
- Viral Latency: The virus enters a dormant state within a host cell, remaining undetected but potentially reactivating under specific conditions (e.g., herpes simplex virus, varicella-zoster virus).
Viral Tropism
- Viral Tropism: The ability of a virus to infect specific cells, tissues, or host species.
- This selectivity depends on the presence of appropriate receptors on the host cell that the virus can bind to.
Common Viruses Relevant to Dentistry
- Human Immunodeficiency Virus (HIV): A retrovirus that attacks the immune system, potentially leading to AIDS.
- Hepatitis B Virus (HBV): A DNA virus that affects the liver, leading to hepatitis B.
- Varicella Zoster Virus (VZV): A DNA virus that causes chickenpox and shingles.
- Herpes Simplex Virus (HSV): A DNA virus that causes oral and genital herpes.
- Influenza Virus: An RNA virus that causes the flu.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
