SNAB Topic 6: Infection, Immunity and Forensics

• What is the process of inflammation?

  • Pathogens enter body.
  • Damaged WBC and mast cells recognise foreign antigen and release histamine.
  • Arterioles in the area dilate so vasodilation occurs around the site, increasing blood flow.
  • Permeability of capillaries also increased so plasma fluid, WBC and antibodies leak into tissue from blood (oedema).
  • Infecting microbes attacked by intact WBC.
• What is an interferon?

  A protein that prevents viruses spreading to infected cells.
• Mechanisms of disease:

  1. Damaging cells.
  2. Producing toxins (Exotoxins secreted by living pathogen, endotoxins released when pathogen is damaged).
• Virus:

  • small organic particles.
  • consist of a strand of nuclei acid (RNA/DNA) surrounded by a protein coat.
  • may have envelope taken from host cell surface membrane
  • envelope has glycoproteins
  • lack internal structures for reproduction so require a host cell for growth/reproduction
  • disturbs working of the host cell and can cause lysis.
• Virus Replication:

  1. Virus attaches to the host cell.
  2. Virus inserts nuclei acid.
  3. Viral nucleic acids replicate.
  4. Viral protein coats synthesised.
  5. New virus particles formed.
  6. Virus particles released due to cell lysis.
• Virus Structure

  A) Capsid

  B) Enzymes

  C) Nucleic acid (RNA/DNa)

  
• Bacterial Cell Structure

  A) Bacterial Chromosome

  B) Pili

  C) Slime Capsule

  D) Cell plasma membrane

  E) Ribosome

  F) Cell wall

  G) Plasmid

  H) Cytoplasm

  I) Flagella

  
• Bacteria:

  • prokaryotic cells
  • no membrane bound organelles
  • 0.5-5 micrometres
  • reproduce asexually via binary fission