BIOL 2303 Lecture Notes - Lecture 9: Hyaluronidase, Cyclic Adenosine Monophosphate, Growth Factor
21 Mar 2016
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Document Summary
Host: the organism that harbours the pathogen. Opportunistic pathogen: an organism that causes disease only when host resistance is compromised (ex/ p. aeruginosa) Pathogenicity: the ability of a microorganism to cause disease, measured in virulence (how many cells does it need) Ld50 (ld = lethal dose): number of pathogen cells that kill 50% of animals in a test group. Here, highly virulent streptococcus pneumoniae only requires ~100 cells to kill 50-100% of mice in a test group. The process by which microorganisms cause disease. Bacteria and viruses often initiate infection by adhering to epithelial cells. Needs specific interactions between pathogen and host molecules. Wide variety of structures involved in adherence. Polysaccharide layers coating the bacterial cells to make them sticky. Slime layer: loose network of polymers extending outside from the cell. Don"t need slime layer or capsule but helps with adherence (ex/ vibrio chlorae) Protection of bacteria from host defense mechanisms.
