Microbiology Chapter 13

  1. What is a virion?
    nucelic acid surrounded by a protein coat
  2. What is a capsid?
    the protein coat
  3. What is a nucleocapsid?
    A capsid with enclosed nucleic acid
  4. What is an enveloped virus?
    A virus with a lipid bilayer outside of the capsid
  5. What is a naked virus?
    • A virus that is not enveloped
    • Most phages
  6. What are the 3 different shapes of viruses?
    • Icosahedral
    • Helical
    • Complex
  7. What does an Icosahedral Virus look like?
    20 flat triangles, resembles a soccer ball
  8. What does a helical virus look like?
    Appears cylindrical, nucleic acid is in a helix
  9. What does complex virus look like?
    Has a complicated structure
  10. What is an arboviruse?
    • spread by arthropods
    • ex mosquitos
  11. What is the Lytic phage infections model?
    T4 phage
  12. What is a lytic/virulent phage?
    • exits host at end of infection cycle via lysing
    • a productive infection
  13. What are the 5 steps of a T4 (lytic/virulent) infection cycle?
    • Attachment
    • Genome Entry
    • Synthesis of Phage proteins and genome
    • Assembly
    • Release
  14. What occurs during the T4 attachment phase?
    • phage collides with host cell by chance
    • attaches to a receptor/pilus on cell that would normally be used for other functions
  15. What occurs during the T4 genome entry phase?
    • post-attachment phage injects it's DNA/RNA into the cell via it's tail degrading a bit of the cell wall with lysozyme
    • After nucleic acid is injected the capsid remains on the cell's surface
  16. What occurs during the T4 Synthesis of phage proteins and genome phase?
    • T4 genes are transcribed and translated quickly
    • Proteins are synthesized to hijack the cells processes
    • Proteins are synthesized to create the phage parts
  17. What occurs during the T4 Assembly phase?
    once all components are synthesized they are assembled into new phage particles with the help of scaffolds
  18. What occurs during the T4 release phase?
    the phage encoded enzyme lysozyme is produced and degrades the cell wall from the inside out causing the cell to lyse
  19. What occurs during Temperate Phage infections?
    The can be lytic or lysogenic
  20. What is the difference between a lytic infection and a lysogenic infection?
    • lytic is a productie infection
    • lysogenic is a latent infection
  21. What occurs during a lysogenic infection?
    • phage's DNA becomes integrated into host's DNA
    • host is called a prophage
  22. What are the consequences of lysogeny?
    • immunity to superinfection
    • lysogenic conversion
  23. What prevents gene excision in a prophage?
    a repressor
  24. What is immunity to superinfection>
    • The same phage cannot reinfect a prophage
    • the repressor which maintains the lysogenic state will repress the incoming phage
  25. What is lysogenic conversion?
    modification of host's properties resulting from expression of phage DNA integrated into the host
  26. What is an example of a temperate infection?
  27. What is a filamentous phage?
    • looks like long fibers
    • causes productive infections that slow down reproduction
  28. What is an example of a filamentous phage?
  29. What occurs during M13 filamentous infection?
    attaches to F pilus and injects itself into cytoplasm where it is synthesized and replicated
  30. What is transduction?
    the transfer of DNA via a phage
Card Set
Microbiology Chapter 13
Microbiology Chapter 13