Kapitel 9 Flashcards
Normal light microscope in which the image is obtained by simple transmission of light through the object being viewed.
bright-field microscope
The proposal that all living organisms are composed of one or more cells and that all cells arise from the division of other living cells.
cell doctrine
Type of light microscope that produces a clear image of a given plane within a solid object. It uses a laser beam as a pinpoint source of illumination and scans across the plane to produce a two-dimensional “optical section.” (Figure 9–19)
confocal microscope
Technique for examining a thin film of an aqueous suspension of biological material that has been frozen rapidly enough to create vitreous ice. The specimen is then kept frozen and transferred to the electron microscope. Image contrast is low - but is generated solely by the macromolecular structures present.
cryoelectron microscopy
Type of light microscopy in which oblique rays of light focused on the specimen do not enter the objective lens - but light that is scattered by components in the living cell can be collected to produce a bright image on a dark background. (Figure 9–7)
dark-field microscopy
Type of light microscope that exploits the interference effects that occur when light passes through parts of a cell of different refractive indices. Used to view unstained living cells.
differential-interference-contrast microscope
Microscope that uses a beam of electrons to create the image.
electron microscope
Technique for viewing three-dimensional specimens in the electron microscope in which multiple views are taken from different directions by tilting the specimen holder. The views are combined computationally to give a three-dimensional image.
electron microscope (EM) tomography
Microscope designed to view material stained with fluorescent dyes or proteins. Similar to a light microscope but the illuminating light is passed through one set of filters before the specimen - to select those wavelengths that excite the dye - and through another set of filters before it reaches the eye - to select only those wavelengths emitted when the dye fluoresces. (Figure 9–12)
fluorescence microscope
Technique for monitoring the kinetic parameters of a protein by analyzing how fluorescent protein molecules move into an area of the cell bleached by a beam of laser light. (Figure 9–29)
fluorescence recovery after photobleaching (FRAP)
Technique for monitoring the closeness of two fluorescently labeled molecules (and thus their interaction) in cells. Also known as Förster resonance energy transfer. (Figure 9–26)
fluorescence resonance energy transfer (FRET)
see fluorescence resonance energy transfer (FRET)
FÖrster resonance energy transfer
see fluorescence recovery after photobleaching
FRAP
see fluorescence resonance energy transfer
FRET
Fluorescent protein isolated from a jellyfish. Widely used as a marker in cell biology. (Figure 9–24)
green fluorescent protein (GFP)
Computer based techniques in microscopy that process digital images in order to extract latent information. Enables compensation for some optical faults in microscopes - enhanced contrast to improve detection of small differences in light intensity - and subtraction of background irregularities in the optical system.
image processing
Method to localize specific macromolecules using a primary antibody that binds to the molecule of interest and is then detected with a secondary antibody to which a colloidal gold particle has been attached. The gold particle is electron-dense and can be seen as a black dot in the electron microscope. (Figure 9–45)
immunogold electron microscopy
Molecules whose light emission reflects the local concentration of a particular ion; some are luminescent (emitting light spontaneously) while others are fluorescent (emitting light on exposure to light).
ion-sensitive indicators
One of a class of microscopes that uses visible light to create the image.
light microscope
In microscopy - the smallest distance apart at which two point objects can be resolved as separate. Just under 0.2 μm for conventional light microscopy - a limit determined by the wavelength of light.
limit of resolution
A piece of fine glass tubing - pulled to an even finer tip - that is used to inject electric current into cells or to study the intracellular concentrations of common inorganic ions (such as H+ - Na+ - K+ - Cl– - and Ca2+) in a single living cell by insertion of its tip directly into the cell interior through the plasma membrane.
microelectrode
A technique in electron microscopy enabling fine detail of isolated macromolecules to be seen. Samples are prepared such that a very thin film of heavy-metal salt covers everywhere except where excluded by the presence of macromolecules - which allow electrons to pass through - creating a reverse or negative image of the molecule.
negative staining
Type of light microscope that exploits the interference effects that occur when light passes through material of different refractive indices. Used to view living cells. (Figure 9–7)
phase-contrast microscope
Technique for studying intracellular processes in which an inactive form of a molecule of interest is introduced into the cell - and is then activated by a focused beam of light at a precise spot in the cell. (Figure 9–28)
photoactivation
Type of electron microscope that produces an image of the surface of an object. (Figure 9–50)
scanning electron microscope
Computational procedure in electron microscopy in which images of many identical molecules are obtained and digitally combined to produce an averaged three-dimensional image - thereby revealing structural details that are hidden by noise in the original images. (Figures 9–54 and 9–55)
single-particle reconstruction
Describes several approaches in light microscopy that bypass the limit imposed by the diffraction of light and successfully allow objects as small as 20 nm to be imaged and clearly resolved.
superresolution
