Kapitel 9

Question 1

Normal light microscope in which the image is obtained by simple transmission of light through the object being viewed.

Answer 1

bright-field microscope

Question 2

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.

Answer 2

cell doctrine

Question 3

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)

Answer 3

confocal microscope

Question 4

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.

Answer 4

cryoelectron microscopy

Question 5

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)

Answer 5

dark-field microscopy

Question 6

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.

Answer 6

differential-interference-contrast microscope

Question 7

Microscope that uses a beam of electrons to create the image.

Answer 7

electron microscope

Question 8

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.

Answer 8

electron microscope (EM) tomography

Question 9

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)

Answer 9

fluorescence microscope

Question 10

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)

Answer 10

fluorescence recovery after photobleaching (FRAP)

Question 11

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)

Answer 11

fluorescence resonance energy transfer (FRET)

Question 12

see fluorescence resonance energy transfer (FRET)

Answer 12

FÖrster resonance energy transfer

Question 13

see fluorescence recovery after photobleaching

Answer 13

FRAP

Question 14

see fluorescence resonance energy transfer

Answer 14

FRET

Question 15

Fluorescent protein isolated from a jellyfish. Widely used as a marker in cell biology. (Figure 9–24)

Answer 15

green fluorescent protein (GFP)

Question 16

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.

Answer 16

image processing

Question 17

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)

Answer 17

immunogold electron microscopy

Question 18

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).

Answer 18

ion-sensitive indicators

Question 19

One of a class of microscopes that uses visible light to create the image.

Answer 19

light microscope

Question 20

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.

Answer 20

limit of resolution

Question 21

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.

Answer 21

microelectrode

Question 22

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.

Answer 22

negative staining

Question 23

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)

Answer 23

phase-contrast microscope

Question 24

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)

Answer 24

photoactivation

Question 25

Type of electron microscope that produces an image of the surface of an object. (Figure 9–50)

Answer 25

scanning electron microscope

Question 26

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)

Answer 26

single-particle reconstruction

Question 27

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.

Answer 27

superresolution