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Definition
Slice through cork
Looked under the compound microscope
Named cell because of latin cella meaning storage (like a cellar) |
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| Schwann (animal) and Schleiden (plant) cells |
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Definition
Cell Theory (published by Schwann without acknowledging anyone else!)
1) The cell is the unit of structure, physiology, and organization in living things.
2) The cell retains a dual existence as a distinct entity and a building block in the construction of organisms.
3) Cells form by free-cell formation, similar to the formation of crystals (spontaneous generation). |
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Term
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Definition
all known living things are made up of cells
the cell is structural & functional unit of all living things
all cells come from pre-existing cells by division. (Spontaneous Generation does not occur)
cells contains hereditary information which is passed from cell to cell during cell division |
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Definition
all cells are basically the same in chemical composition
all energy flow (metabolism & biochemistry) of life occurs within cells |
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Definition
| Magnification - enlarge an image, but it will not necessarily be better at high magnification. Loss of resolution |
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Definition
| Resolution - the minimal distance between two objects allowing each object to be viewed separate from the other |
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| Magnification and Resolution |
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Definition
| Eyepiece and objective give you two forms of magnification. Multiply them together to get total magnification. |
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Term
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Definition
Resolution 0.61(WLENGTH)/n sin theta.
If you use a long wavelength, then the resolution will be a big number, meaning you have to have two things far apart in order to distiguish them as two separate items. Therefore, shorter wavelength light gives a better resolution! |
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Term
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Definition
| Bright Field, DIC (Normarsky), Phase contrast, Dark Field |
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Term
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Definition
Light is scattered going through matter
Differences in scatter alter the phase of waves of light
Computer-assisted differential-interference contrast microsopy (DIC) |
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Term
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Definition
| Bright field (used for stained or naturally pigmented specimens) |
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Term
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Definition
| Phase contrast (adds 1/4 wavelength to make bigger differences that the eye can see) |
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Term
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Definition
| - differential interference contrast (splits the light prior to the sample with a prism to get a shadowing effect - gives pseudo 3D image without halos) |
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Definition
| (illuminate from the side, collect diffracted light - gives light on dark backround) |
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Term
| . Fixing and staining cells |
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Definition
Fixing - means killing, immobilizing and preserving
Use formaldehyde and glutaraldehyde
crosslinks free amino groups
where do you find free amino groups? |
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Definition
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Term
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Definition
| - often react based on binding to charged amino acids or molecules |
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Term
| Staining, protein-protein interactions |
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Definition
| Binding a stain to specific molecules through protein-protein interactions |
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| Staining Hemotoxylin (red) |
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Definition
| - binds negatively charged molecules (DNA) |
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Term
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Definition
Use of antibodies
Primary versus secondary antibody
Signal is amplified because more than one secondary antibody binds to primary antibody |
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Definition
Antibody made by a rabbit that recognizes antigen A
Antibody made by a goat that recognizes rabbit antibodies |
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Definition
| Fluorescence - molecule absorbs light energy and gets excited; gives off light at a lower (longer wavelength) energy |
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Term
| Three dimensional structures Optical section - |
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Definition
| reject out of phase light |
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Term
| Three dimensional structures Image deconvolution - |
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Definition
refocus out of focus light after image acquisition
using computer software and algorithms |
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Term
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Definition
Manipulates light - almost always fluorescence
Specific - Uses lasers to pinpoint light at a particular depth in the sample
Place a detector to collect the emitted light at the exact spot where the rays are focused (confocal)
Out of focus emitted light is not collected - reducing interference |
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Term
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Definition
| Fluorescent light emitted from sample at a particular depth that is focused on the detector is collected |
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Definition
| Fluorescent light emitted from sample from other depths is out of focus on the detector and is mostly not collected |
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Definition
Higher energy (shorter wavelenth) = greater resolution
Beam of electrons (energy, but not light) - form of radiation
100 times better resolution than light microscope |
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Term
| The higher the atomic number of the atoms in the specimen, |
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Definition
| more the electrons are scattered and greater the contrast… due to the size of the nucleus (protons and neutrons) |
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Term
| Electron microscopy preparation involves |
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Definition
staining samples with salts of heavy metals
(uranium and lead) |
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Term
| Transmission EM - shows the inner detail of cells |
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Definition
Samples placed in a vacuum
Samples are stained with electron dense material - necessary to scatter electrons as they pass through the sample
Samples are cut very thin because electrons can’t penetrate very deeply
Dense regions show up as dark |
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Term
| Scanning EM - shows the detail of the outside of a sample |
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Definition
Specimen coated with thin layer of heavy metal
Collects scattered electrons
Three-dimensional image of outside of specimen |
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| Main limitations in Electron Microscopy |
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Definition
Sample preparation - removal of water (how natural is that?)
Freezing to preserve structure and staining with heavy metals |
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