Viruses

• What are viruses considered in terms of living status?

  Non-living particles
• Why are viruses considered non-living?

  They need a host cell to reproduce
• What is the size range of viruses?

  20 to 400 nanometers
• What type of genetic material do viruses contain?

  Either DNA or RNA
• What is the protective protein coat of a virus called?

  Capsid

  
• What are the shapes of virus capsids?

  • Spherical
  • Polyhedral
  • Helical
  • Complex

  
• What do binding sites on viruses do?

  Allow attachment to host cells
• What are the characteristics of life in viruses?

  1. Reproduction by invading host cells
  2. Mutation leading to new strains
• What virus infects tobacco plants?

  Tobacco Mosaic Virus
• Which virus infects humans' upper respiratory tract?

  Common Cold Virus
• What virus infects immune system cells?

  Human Immunodeficiency Virus (HIV)
• What are common diseases caused by viruses?

  • Influenza
  • Polio
  • Measles
  • AIDS
  • Mumps
  • Common cold
  • Rabies
  • COVID-19
• How are viruses classified?

  By orders, families, genera, and species
• How many virus species have been identified?

  Over 4,000 species
• What is host specificity in viruses?

  Viruses infect specific hosts or related species
• How do viruses transmit?

  • Airborne or direct contact
  • Insect bites
  • Through injuries
• What are the key differences between viroids, prions, and viruses?

  • Viroids: Infectious RNA, no protein coat
  • Prions: Misfolded proteins, no RNA/DNA
  • Viruses: DNA/RNA and protein coat
• What is a bacteriophage?

  A virus that infects bacteria
• How do bacteriophages reproduce?

  By injecting genetic material into bacteria
• What are the two ways viruses can reproduce?

  1. Lytic cycle
  2. Lysogenic cycle

  
• What are the steps of the lytic cycle?

  1. Attachment
  2. Entry
  3. Replication
  4. Assembly
  5. Lysis (Release)

  
• What happens during the attachment step of the lytic cycle?

  The virus attaches to a host cell

  
• What occurs during the entry step of the lytic cycle?

  Virus injects DNA/RNA into the cell

  
• What happens during the replication step of the lytic cycle?

  Host cell makes copies of viral DNA/RNA

  
• What occurs during the assembly step of the lytic cycle?

  New virus particles are assembled

  
• What happens during the lysis step of the lytic cycle?

  Host cell breaks open and releases viruses

  
• What is the lysogenic cycle?

  • A viral reproduction cycle
  • Integrates viral DNA into host DNA
  • Can remain dormant before entering lytic cycle