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Microbiology BACTERIA I. Eukaryote vs. Prokaryote I. Eukaryote vs. Prokaryote II. The Three Domains II. Bacteria vs. Archaea (vs. Eukarya) II. The Three Domains III/IV. Classification III. Archaea Classification 1. Euryarchaeota - methanogens (produce methane) - thermophiles (high temperatures) - halophiles (high salt) III. Archaea Classification 2. Crenarchaeota - thermophilic - sulfur dependent III. Archaea Classification 3. Korarchaeota - high temperature hydrothermal environments III. Archaea Classification 4. Nanoarchaeota (contains one species) - one of the smallest organisms in the world - parasitic - thermophilic III. Bacteria Classification 1. Proteobacteria (gram-negative) - pathogenic parasites - free-living nitrogen fixation Escherichia coli III. Bacteria Classification 2. Chlamydiae (gram-negative) - obligate intracellular pathogens Chlamydia trachomatis III. Bacteria Classification 3. Spirochetes (gram-negative) - double membrane - long, corkscrew-shaped cells Treponema pallidum III. Bacteria Classification 4. Cyanobacteria (gram-negative) - photosynthetic - blue-green bacteria Tolypothrix sp. III. Bacteria Classification 5. Gram-Positive Bacteria - positive result in gram stain test (purple) - absence of outer membrane - more susceptible to antibiotics Bacillus anthracis V. Gram Staining - Gram-positive bacteria take up the crystal violet stain used in the test, and then appear to be purple-coloured when seen through a microscope. - This is because the thick peptidoglycan layer in the bacterial cell wall retains the stain after it is washed away from the rest of the sample, in the decolorization stage of the test. Bacillus anthracis Tolypothrix sp. V. Gram Staining - Gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in this stage degrades the outer membrane of gramnegative cells making the cell wall more porous and incapable of retaining the crystal violet stain. - Their peptidoglycan layer is much thinner and sandwiched between an inner cell membrane and a bacterial outer membrane, causing them to take up the counterstain (safranin or fuchsine) and appear red or pink. VI. Cell Shape & Grouping VII. Motility https://www.youtube.com/watch?v=zlFRJftA2b U VII. Motility - Flagella: Most motile bacteria move by the use of flagella (singular, flagellum), rigid structures 20 nm in diameter and 15-20 µm long, which protrude from the cell surface - E.g. Salmonella VII. Motility - Spiraling: Spirochetes have a specialized internal structure known as the axial filament, which is responsible for rotation of the cell in a spiral fashion and consequent locomotion - E.g. Lyme disease VII. Motility - Gliding: Gliding bacteria all secrete copious slime, but the mechanism that propels the cells is not known - E.g. Disease that affects poultry VIII. Bacterial Reproduction SEE POSTED NOTES on: ASEXUAL REPRODUCTION A. Binary Fission B. Budding C. Sporulation SEXUAL REPRODUCTION D. Gene transfer through conjugation E. Plasmid transfer through conjugation IX. Antimicrobial Resistance https://www.youtube.com/watch?v=oll8PGmunR0 IX. The End of Antibiotics https://www.youtube.com/watch?v=M6YqystsKb4
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