Term
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Definition
| What is the shortest wavenlength that in result gives the highest resolution? |
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Term
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Definition
- light bends as it passes through specimen into air- reduces resolving power
- If space between specimen and objective is replaced with _____ oil, resolution increases |
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Term
| stain the cell or a special type of microscope |
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Definition
| How can you increase the contrast of bacteria? |
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Term
| crystal violet, methylene blue, safranin |
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Definition
| many stains are basic dyes. What are some examples? |
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Term
Chromophore has a (+) charge
Cell surface has a (-) charge |
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Definition
Chromophore has a ______ charge
Cell surface has a _____ charge |
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Term
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Definition
| Simple stains can differentiate between types of cells or structures. T/F? |
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Term
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Definition
| Distinguish between different types of bacteria or different structures |
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Term
Gram stain
Acid-fast stain |
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Definition
| What are two different types of differential stains? |
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Term
Gram stain
Acid-fast stain |
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Definition
distinguishes Gram positive bacteria from Gram negative bacteria
distinguishes Mycobacterium species from other bacteria |
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Term
Microscope we typically use is called bright-field light microscope
See stained cells on bright background
Instead of staining cells, special microscopes can be used to increase contrast between cells & medium |
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Definition
| Types of Microscopes Used To Increase Contrast? |
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Term
a special ring inside the lens
-cells bend light more and the
special rings exagerrate this
making it easier to be seen |
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Definition
| How is the difference in “phase” amplified in a phase contrast microscope. |
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Term
Can observe living cells in wet mount
Can see organelles of eukaryotes |
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Definition
| What are phase-contrast microscopes used to view? |
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Term
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Definition
| What can dark-field microscopy see that light microscopy cannot? |
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Term
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Definition
| What microscopy is excellent for studying bacterial motility & very narrow cells? |
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Term
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Definition
o Cells appear bright against dark background
o Dark-field stop in condenser doesn’t let light pass directly through specimen
Only light scattered by sample reaches
objective
o Can observe living cells in wet mount, and narrow cells and cell structures (flagella), and spirochete cells
o Problem - dust particles also scatter light |
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Term
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Definition
| the light ray passes through a filter which has a single, preferred vibration direction |
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Term
| Differential Interference Contrast (DIC) Microscopy |
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Definition
o Polarized light passes through specimen
o Sample boundaries bend light
o Second polarized lens blocks light
o Bent light results in 3D appearance of object |
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Term
| Differential Interference Contrast (DIC) Microscope |
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Definition
| What microscope gives the object a 3D appearance? |
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Term
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Definition
-Some compounds absorb energy from _invisible radiation_ (like short
wavelength UV light) then radiate energy back as longer, visible wavelength.
-Fluorophores absorb high-energy light (short wavelength) then emit lower-energy light (longer wavelength)
-Used to view cells that make fluorescent compounds such as chlorophyll, or cells that have been stained with fluorescent dyes
-These microscopes use a UV light light source to fluoresce objects
-Can label molecules of interest in cell |
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Term
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Definition
| Used to view cells that make fluorescent compounds such as chlorophyll |
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Term
1) high-energy light (short wavelength)
2)lower-energy light (longer
wavelength) |
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Definition
| Fluorophores absorb 1)______________ then emit 2)______________ |
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Term
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Definition
| Flourescence microscopes use a __________ to flouresce objects |
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Term
| The wavelength of light used |
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Definition
| Resolving power of light microscopes is limited by |
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Term
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Definition
| Can magnify over 100,000x |
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Term
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Definition
| this microscope can be used to view viruses, proteins, nucleic acids |
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Term
Electron microscope
(reflect _electrons_) |
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Definition
For this type of microscope the sample must:
reflect ________
be coated with a heavy metal |
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Term
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Definition
| with an electron microscope the electron beam and sample are... |
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Term
| Transmission Electron Microscope |
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Definition
| With this type of microscope the sample is sliced very thin |
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Term
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Definition
| This is used to slice a sample that is being observed with a TEM. Some can slice up to 20x |
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Term
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Definition
| When using a TEM the sample must be coated with what? |
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Term
| Transmission Electron Microscope |
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Definition
o Electrons travel through specimen
o Gives extremely High resolution
o Used to view cell structures, DNA &
some protein molecules |
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Term
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Definition
Used to view cell structures, DNA & some protein molecules
Used to visualize surface cell structures |
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Term
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Definition
| Does TEM or SEM give a better resolution? |
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Term
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Definition
| The sample is sliced for an SEM microscope. T/F? |
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Term
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Definition
| The sample is sliced for a TEM microscope. T/F? |
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Term
| Scanning Electron Microscope (SEM) |
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Definition
o Sample is coated with heavy metal
o Not sliced
o retain 3D image
o Gives 3D image
o Image formed from electrons
o Used to visualize surface cell structures |
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Term
| Leprosy (Hansen's disease) |
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Definition
| What is caused by Mycobacterium leprae? |
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