Lecture 6 (Quiz 3)

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  1. Fluorescence Microscopy
    • Also can fuse DNA from fluorescent protein to a gene of interest (Protein Tagging)
    • Fluorescent protein is then made any time your gene is made
    • No antibodies needed
    • We are able to see the proteins that are being made inside of the cell with color
    • Some bacteria can be naturally fluorescent
  2. Confocal Microscopy
    • Version of Fluorescence Microscopy
    • Cover everything with fluorescent dye
    • 3D Images
    • Laser scanning
    • Puts image back together again
    • UV light is used
  3. Digital Microscopy
    • The scope analyzes the bacteria in the computer itself
    • Advantages: It's done quickly, online, and it's easy to share with others
    • Disadvantages: Limited power, costs a lot of money ($500,000-$1,000,000)
  4. Electron Microscopes
    • No light waves, electrons, good for very small
    • things
    • They are used with vaccum sealed air. When electrons are shot down, they must be vaccumed up or else they would scatter.
    • Electromagnets: They focus the beams of electrons since there are NO lenses.
  5. Scanning vs. Transmission? (Electron Microscopes)
    • Transmission: The specimen is in a thin section of plastic, it's see through
    • Scanning: At the bottom of the scope, cover with metal (electrons bounce off, computer records 3D images, artificially colored)
    • The images are colored afterwards
  6. Scanning Tunneling Microscopy (STM)
    • You run a metal probe over a surface
    • Electrons interact and create a current
    • It can get down to visualize the individual atomic level
    • 3D Structures
    • Like reading braille
  7. Atomic Force Microscopy (AFM)
    • Visualizing atoms to 1 micrometer
    • The technology is newer
    • It has the same idea as STM
    • 3D Structures
    • Like reading braille
  8. Wet Mounts - Regular vs. Hanging Drop?
    • Regular Slide: A drop of cells is put on a flat surface, more difficult to see since the cells are spread out over such a large surface area.
    • Hanging Drop: Instead of being flat, there's a divot where the drop is placed and organisms are better seen. However, more expensive.
  9. Smears
    • Must air dry before heat fixing because if not, you'll end up boiling the cells and killing them
    • 3 Things of Heat Fixing: Kills bugs, denatures proteins so they adhere to the slide, makes bugs take up dye easier.
  10. Stains
    Most are basic (+) so they are attracted to bacteria cell walls (-)
  11. Simple Stain vs. Differential Stain
    • Simple Stain: Everything is the same color
    • Differential Stain: For gram staining, 2 or more dyes (different cells are different colors)
  12. Gram Stains - Which are used? Color? Order?
    • Crystal Violet: Turns everything purple
    • Iodine: Mordant, it locks in Gram +
    • Alcohol: Turns Gram - invisible
    • Safranin: Turns the invisible Gram - cells pink
    • If one of the steps is missed, the cells will be misinterpretted and all will become crystal violet
  13. Acid Fast/Negative Stain
    • Sometimes bacteria have an outer capsule on top of the peptidoglycan that makes the bacteria invisible in out bodies, so then they won't stain
    • This type of staining will help us see the actual cells (which are dangerous) with the clearing around them
  14. Flagellar Stain
    Use a metal stain with a hanging drop to see the bacteria around the flagella
  15. Endospore Stain
    Heat is used to break down the spore wall and the inside becomes green
  16. Prokaryotic Cells
    • Pro=Before, Karyon=Nucleus (Before Nucleus)
    • For Eukaryotic: Eu=True (True Nucleus)
    • Some big  difference between Pro and Euk: Nucleus, Circular DNA vs. Linear, and true organelles are only in Eukaryotes
  17. Cell Groupings
    • Single: Only one
    • Diplo: Two stuck together
    • Strepto: Chain
    • Staphylo: Circular cluster
    • Tetrad: 4 circular
    • Sarcinae: 8 circular
  18. Shapes of Cells
    • Bacillus: Long
    • Cocci: Circular
    • Vibrio: Comma-shaped
    • Spirillium: Wave-like, ALWAYS have flagellum
    • Spirochete: Wavier, DO NOT have flagellum
  19. Cell Wall
    • NAG and NAM: Sugars, chain-link fence, make up peptidoglycan
    • Peptide cross bridges
  20. Gram +
    • Cell membrane, and then a thick wall of Peptioglycan on top.
    • Contains Teichoic Acid which fixes in the gram stain (purple).
    • Makes exotoxin, which is not attached.
  21. Gram -
    • Cell membrane, thin layer of peptidoglycan, and outer membrane 
    • Periplasmic Space: Digestive enzymes and protein pumps
    • Lipid contains endotoxin (LPS) which is inside the cell and permanently stuck in the outer membrane.
  22. Acid Fast Cell Wall - what makes it different?
    There is a thick lipid layer on the outer part of the cell wall (mycolic acid) that repels stains (found in TB and leprosy)
  23. The 2 acids for Gram +?
    • Teichoic Acid: Iodine sticks to it to get crystal violet stain 
    • Mycolic Acid: Repels stains
Card Set:
Lecture 6 (Quiz 3)
2015-04-25 22:56:00
microscope, cells walls, etc.
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