Micropara

• Virus


  Can be considered as living or non-living cell, obligate intracellular particle, contains a single type of genome (complete set of genetic material), has protein coat in the form of capsid, some have envelope (bilayer of protein substances), uses synthetic machinery for replication, cannot be inactivated using antibiotics, can produce new specialized elements, comes in different shapes (icosahedral, helical symmetry, complex symmetry)
• DNA


  Instructional manual, replicates inside the nucleus
• RNA


  Targets ribosomal part
• All viruses have capsid
• Envelope


  Serves as attachment, virulent factor
• Capsid


  Protein shell that surrounds the genome, protects the viral genome and introduces viral into host cells
• Types of viruses


  • Human/Animal viruses (respiratory, enteric, arbovirus)
  • Plant viruses
  • Insect viruses
  • Bacteria viruses (bacteriophage)
• Basic stages of virus multiplication


  1. Attachment

  2. Penetration

  3. Uncoating

  4. Replication/Gene expression

  5. Assembly

  6. Release
• Penetration


  Virus has gained entry into the host cell, can happen through 4 ways (translocation, endocytosis, fusion, direct fusion)
• Uncoating


  Process in which viral capsid is degraded by viral enzyme or host enzyme, releasing the viral genomic nucleic acid
• Replication/Gene expression


  Synthetic machinery, lytic cycle (virulent cycle), lysogenic cycle (dormant, temperate cycle)
• Assembly


  Mature or stable state of rest, viral assembly may take place in the cytoplasm of the cell
• Release


  Possible by cell lysis, cell degeneration, or budding
• Components of a virus


  • Viral genome (nucleic acid)
  • Capsid
  • Spikes (carbohydrate-protein complexes)
• Types of viral genomes


  • Double-stranded DNA
  • Single-stranded DNA
  • Single-stranded RNA (negative-stranded, positive-stranded)
  • Double-stranded RNA
• Positive-stranded RNA virus


  Viral mRNA can directly bind to ribosome to synthesize proteins
• Negative-stranded RNA virus


  Needs a template to synthesize complementary strand of RNA
• Retrovirus


  Carries its own enzyme called Reverse Transcriptase to integrate into the DNA of a host cell
• Viroids


  Plant viruses, obligate parasites, lack structural proteins