Lecture 6 (Quiz 3)
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Lecture 6 (Quiz 3)
microscope, cells walls, etc.
Also can fuse DNA from fluorescent protein to a gene of interest (
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
Version of Fluorescence Microscopy
Cover everything with fluorescent dye
Puts image back together again
UV light is used
The scope analyzes the bacteria in the computer itself
: It's done quickly, online, and it's easy to share with others
: Limited power, costs a lot of money ($500,000-$1,000,000)
No light waves, electrons, good for very small
They are used with vaccum sealed air. When electrons are shot down, they must be vaccumed up or else they would scatter.
: They focus the beams of electrons since there are NO lenses.
Scanning vs. Transmission? (Electron Microscopes)
: The specimen is in a thin section of plastic, it's see through
: At the bottom of the scope, cover with metal (electrons bounce off, computer records 3D images, artificially colored)
The images are colored afterwards
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
Like reading braille
Atomic Force Microscopy (AFM)
Visualizing atoms to 1 micrometer
The technology is newer
It has the same idea as STM
Like reading braille
Wet Mounts - Regular vs. Hanging Drop?
: 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.
: Instead of being flat, there's a divot where the drop is placed and organisms are better seen. However, more expensive.
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.
Most are basic (+) so they are attracted to bacteria cell walls (-)
Simple Stain vs. Differential Stain
: Everything is the same color
: For gram staining, 2 or more dyes (different cells are different colors)
Gram Stains - Which are used? Color? Order?
: Turns everything purple
: Mordant, it locks in Gram +
: Turns Gram - invisible
: Turns the invisible Gram - cells pink
If one of the steps is missed, the cells will be misinterpretted and all will become crystal violet
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
Use a metal stain with a hanging drop to see the bacteria around the flagella
Heat is used to break down the spore wall and the inside becomes green
Pro=Before, Karyon=Nucleus (Before Nucleus)
: Eu=True (True Nucleus)
Some big difference between Pro and Euk
: Nucleus, Circular DNA vs. Linear, and true organelles are only in Eukaryotes
: Only one
: Two stuck together
: Circular cluster
: 4 circular
: 8 circular
Shapes of Cells
: Wave-like, ALWAYS have flagellum
: Wavier, DO NOT have flagellum
NAG and NAM
: Sugars, chain-link fence, make up peptidoglycan
Peptide cross bridges
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.
Cell membrane, thin layer of peptidoglycan, and outer membrane
: Digestive enzymes and protein pumps
(LPS) which is inside the cell and permanently stuck in the outer membrane.
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)
The 2 acids for Gram +?
: Iodine sticks to it to get crystal violet stain
: Repels stains