Deck 18: Techniques in Cell and Molecular Biology

Question 1

The fluorescence imaging method in which a specimen containing one or more photoswitchable fluorophores is illuminated with pulses of light is known as:

A)fluorescence recovery after photobleaching
B)laser scanning confocal microscopy
C)super-resolution microscopy
D)light sheet microscopy
E)fluorescence resonance energy transfer

Answer 1

C

Question 2

Of what is the electron source of an electron microscope, the cathode, composed?

A)a tungsten wire filament
B)an iron wire filament
C)a titanium wire filament
D)an iron spike filament
E)a tungsten depressor filament

Answer 2

A

Question 3

How do you prepare tissue for electron microscopy without using fixatives?

A)Freeze it gradually over a few hours.
B)Freeze it rapidly.
C)Subject it to a vacuum rapidly.
D)Heat it to dry it rapidly.
E)Coat it quickly in heavy metal.

Answer 3

B

Question 4

Why is it that with a standard transmission electron microscope, resolution is actually about two orders of magnitude less than its theoretical limit?

A)The lenses of an electron microscope exhibit serious spherical aberration problems, which can be avoided by using a very small N. A.
B)The lenses of an electron microscope exhibit serious spherical aberration problems, which can be avoided by using a very large N. A.
C)If electron wavelength is too high, spherical aberration distorts the image.
D)If electron wavelength is too low, spherical aberration distorts the image.

Question 5

The 3-D computerized reconstruction of a cell generated by cryoelectron tomography is called a(n)________.

A)tomatogram
B)chromatogram
C)tomogram
D)telegram
E)tonogram

Question 6

Which electron microscope technique is used to create a three-dimensional image of the surfaces of objects ranging in size from a virus to an animal's head?

A)positive staining
B)negative staining
C)scanning electron microscopy
D)shadow casting
E)freeze-fracture freeze-etch

Question 7

The total magnification of a microscope is equal to __________.

A)the product of magnification produced individually by the ocular and the condenser lens
B)the product of magnification produced individually by the ocular and objective lenses
C)the magnification power of the objective lens divided by the numerical aperture
D)the magnification power of the ocular lens divided by the numerical aperture
E)the magnification power of the objective lens divided by that of the ocular lens

Question 8

What is the name of the special device used to section a frozen block of tissue?

A)micrometer
B)cryoslicer
C)cryomicrotome
D)ultratome
E)microslicer

Question 9

Molecules which absorb photons of a specific wavelength and release a portion of the energy in longer wavelengths are called ________.

A)fluorophores
B)absorbers
C)fluorocules
D)emitters
E)glow molecules

Question 10

An electron beam strikes a specimen in an area where there is a high concentration of heavy metal atoms. What does a spot on the phosphorescent screen of the electron microscope just below this part of the specimen look like if compared to the area of the specimen where there is the high concentration of heavy metal atoms?

A)It is darker.
B)It is brighter.
C)It is speckled.
D)It is invisible.
E)It is purple.

Question 11

How does a phase-contract microscope setup make transparent objects more visible?

A)It uses brighter bulbs than conventional light microscopes.
B)It generates a negative image so that the background is dark and the specimen is light.
C)It generates stereo images that can be viewed only with polarized filters.
D)It causes direct and refracted light rays to interfere with one another.
E)It operates at a lower temperature to reduce random specimen movement.

Question 12

Which of the following is NOT a commonly used fluorophore?

A)GFP
B)CFP
C)EPuce
D)EYFP
E)mBanana

Question 13

With what molecules in a cell does osmium tetroxide primarily react?

A)DNA
B)RNA
C)fatty acids
D)proteins
E)carbohydrates

Question 14

Which part of a microscope is responsible for gathering diffuse rays from the microscope light source and illuminating the specimen with a small cone of bright light?

A)condenser lens
B)objective lens
C)ocular lens
D)iris
E)focusing knob

Question 15

Two fluorescent proteins (protein 1 and protein 2)are used in a FRET experiment and are illuminated with light that excites protein 1. If the proteins are close enough for energy transfer to occur, what wavelength(s)of light will be detected?

A)The light that excites protein 1
B)The light that is emitted by protein 1
C)The light that excites protein 2
D)The light that is emitted by protein 2
E)No light will be detected, because the fluorescence of proteins 1 and 2 will cancel out

Question 16

What describes the result of the magnification power of the microscope exceeding the ability of the microscope to resolve?

A)empty resolution
B)waste
C)empty magnification
D)refractibility
E)birefringence

Question 17

Why do electron microscopes provide much greater resolving power than light microscopes?

A)more electrical power is involved in running an electron microscope
B)the wavelength of an electron is much smaller than that of visible light
C)the wavelength of an electron is much larger than that of visible light
D)the numerical aperture is much larger in electron microscopes
E)the numerical aperture is much smaller in electron microscopes

Question 18

Advanced optical techniques such as stochastic optical reconstruction microscopy (STORM)have lowered the optical microscope resolution limit to less than ________.

A)0.02 µm
B)0.2 µm
C)2 µm
D)20 µm
E)200 µm

Question 19

What is NOT an advantage of capturing the image generated by transmission electron microscopy using a CCD video camera?

A)It provides an instant image.
B)There is no need to develop the image using chemicals.
C)The image can be captured at very high resolution.
D)Less voltage is required.

Question 20

Good fixatives are chemicals that _______ and ________ cellular macromolecules without producing artifacts.

A)precipitate, degrade
B)degrade, denature
C)denature, precipitate
D)denature, polarize
E)polarize, precipitate

Question 21

What determines the identity and chemical properties of an atom?

A)the number of protons in its nucleus
B)the number of neutrons in its nucleus
C)the number of electrons in its nucleus
D)the number of protons in the atom's electron shells
E)the number of neutrons in the atom's electron shells

Question 22

Atomic force microscopy can be used for ___________.

A)the monitoring and determination of molecular structure
B)nanomanipulation to pull or push on a specimen in an attempt to measure various mechanical properties
C)determination of the affinity of a receptor for its ligand
D)visualization of macromolecular activity over time
E)All of these are true.

Question 23

________ are atoms with the same number of protons but varying numbers of neutrons.

A)Isomers
B)Isosceles
C)Isotopes
D)Epitopes
E)Haplotypes

Question 24

Why must a specimen that is to be viewed in the SEM be dehydrated before viewing?

A)Water causes the specimen to swell.
B)Water distorts the image.
C)The specimen will be observed in a vacuum, which would cause the water to freeze.
D)The specimen will be observed in a vacuum, which would cause the water to evaporate rapidly and damage the specimen, altering its surface structure.
E)Water attracts electrons.

Question 25

How do enzymes like trypsin release cells from tissues to create preparations of single cells?

A)The enzymes digest extracellular domains of proteins that mediate cell adhesion.
B)The enzymes digest intracellular domains of proteins that mediate cell adhesion.
C)The enzymes digest intracellular domains of proteins that mediate cytoskeletal function.
D)The enzymes digest extracellular domains of proteins that mediate cytoskeletal function.
E)The enzymes digest extracellular domains of proteins that mediate endocytosis.

Question 26

A ________ is a substance that reveals its presence in one way or another and thus can be localized or monitored during an experiment.

A)trancer
B)tracer
C)phosphor
D)fluor
E)trancept

Question 27

_________ are established with cells that have been frozen in liquid nitrogen, thawed and then placed in a waiting culture medium.

A)Primary cultures
B)Secondary cultures
C)Tertiary cultures
D)Supernatant cultures
E)Penultimate cultures

Question 28

After plant cells have been separated and grown in culture, they can grow into an undifferentiated clump of cells called a __________.

A)callus
B)plaque
C)blastema
D)tumor
E)blastula

Question 29

Which form of radiation is emitted by the most commonly used isotopes and by most biologically important isotopes?

A)an alpha particle
B)a delta particle
C)a beta particle
D)gamma radiation
E)an omega particle

Question 30

When a cell is growing on a culture dish, what is the word that refers to the lower surface of the cell facing toward the substratum?

A)anterior
B)dorsal
C)posterior
D)ventral
E)caudal

Question 31

A culture system in which cells are grown in a multi-dimensional matrix consisting of synthetic and/or natural extracellular materials is called a ______.

A)three-dimensional culture system
B)two-dimensional culture system
C)matrix culture system
D)secondary culture system
E)organic culture system

Question 32

When specimens are air-dried, what causes the damage that the tissues suffer?

A)shrinkage
B)swelling
C)surface tension at air-water interfaces
D)hydrostatic pressure
E)air pressure

Question 33

Which form of radiation is equivalent to a helium atom nucleus?

A)an alpha particle
B)a delta particle
C)a beta particle
D)gamma radiation
E)an omega particle

Question 34

In which technique is radioactivity detected by mixing the sample in a vial with a special fluid that contains compounds that emit light if struck by a beta particle?

A)autoradiography
B)an NMR machine
C)liquid scintillation spectrometry
D)mass spectrometry
E)AFM

Question 35

Which of the following is a technique used to isolate a particular organelle in bulk so that its function can be studied or so that an enzyme can be isolated from it?

A)differential interference contrast microscopy
B)differential centrifugation
C)affinity chromatography
D)selective precipitation
E)autoradiography

Question 36

In phage display, the antibody molecule is displayed on the _______.

A)inner surface of the viral particle
B)outer surface of the viral particle
C)viral DNA
D)viral RNA
E)viral carbohydrates

Question 37

__________ are established with cells that have been obtained directly from the organism; cultures produced from animal cells are usually obtained from ________.

A)Primary cultures, embryos
B)Secondary cultures, adult organisms
C)Primary cultures, adult organisms
D)Secondary cultures, embryos
E)Secondary cultures, primary cultures

Question 38

What happens if a photographic emulsion is brought into close contact with a radioactive source in a specimen?

A)The emulsion is degraded in places close to a radioactive atom.
B)The particles emitted by the source leave tiny, black silver grains in the emulsion after photographic development.
C)The particles emitted by the source leave tiny, black potassium grains in the emulsion after photographic development.
D)The particles emitted by the source leave tiny, silver carbon grains in the emulsion after photographic development.
E)The particles emitted by the source leave tiny, gold atoms in the emulsion after photographic development.

Question 39

What method is typically used to dry specimens for scanning electron microscopy?

A)air drying
B)critical-point drying
C)forced air drying
D)vacuum drying
E)dehydrational drying

Question 40

What typically happens if the cells of a cell line are injected into laboratory animals?

A)They become a normal part of the appropriate tissue in the lab animal.
B)The cells soon die.
C)They typically grow into malignant tumors.
D)They typically grow into the appropriate organ.
E)They become part of organs.

Question 41

Which technique depends on the use of antibodies made specifically against a particular protein (antigen)and then conjugated to a substance that makes the antibodies visible under the light or electron microscope?

A)immunolocalization
B)immunocompetence
C)immunization
D)immunofenestration
E)negative staining

Question 42

What technique distributes the contents of a homogenate into various layers according to the components' densities?

A)sucrose density gradient centrifugation
B)sucrose density chromatography
C)isoelectric density focusing
D)liquid scintillation spectrometry
E)autoradiography

Question 43

What is the general term used to describe a variety of techniques in which a mixture of dissolved components is separated as it moves through a porous matrix?

A)electrophoresis
B)isoelectric focusing
C)chromatography
D)selective precipitation
E)sucrose density centrifugation

Question 44

If you are illuminating a specimen with ultraviolet light, into what kind of container should it be placed to make a measurement in a spectrophotometer?

A)in a basinette
B)in a special, flat-sided quartz container
C)in a borosilicate glass tube
D)in a special, flat-sided glass container
E)in a special, flat-sided plastic container

Question 45

The amount of light passing through a solution unabsorbed (or _________)is measured by a ___________ on the other side of the cuvette.

A)transmitted, thermocouplers
B)absorbed, thermocouplers
C)transmitted, photosensor
D)absorbed, photosensor
E)transmitted, charged coupling devices

Question 46

To what are the reflection positions and intensities on the photographic plate of an X-ray crystallography experiment related?

A)proton densities of proteins
B)neutron densities of proteins
C)electron densities of proteins
D)proton densities of nucleic acids
E)neutron densities of lipids

Question 47

Non-denaturing gel electrophoresis (PAGE)has the disadvantage that it ____________.

A)separates solely on the basis of charge
B)allows the detection of proteins in a gel by their biological activity
C)separates on the basis of more than one property thus to some degree confusing the results
D)separates solely on the basis of molecular weight
E)separates on the basis of molecular weight and frictional coefficient

Question 48

Under what set of circumstances will organelles move to the bottom of a centrifuge tube in a centrifugal field?

A)if the organelle is smaller than ribosomes
B)if the organelle has too much fat content
C)if the organelle is less dense than the surrounding medium
D)if the organelle is more dense than the surrounding medium
E)if the organelle has less fat content than the surrounding medium

Question 49

For higher resolution cryo-EM studies, what has replaced the use of negatively stained specimens?

A)frozen-dehyhdrated particles
B)positively stained specimens
C)frozen-hydrated particles
D)neutrally stained specimens

Question 50

How are fragments already in a mass spectrometer further fragmented?

A)injection of pepsin
B)injection of more trypsin
C)collision of peptides with an inert gas
D)collision of peptides with nitrogen gas
E)collision of peptides with oxygen

Question 51

What is the name of the procedure in which proteins separated on a polyacrylamide gel are transferred with the application of a current to a nitrocellulose filter placed against the gel and subsequently identified by their interaction with specific antibodies?

A)a Southern blot
B)a Northern blot
C)an Eastern blot
D)a Western blot
E)an East Northeastern blot

Question 52

In the yeast two-hybrid assay, the _________ domain and the _________ domain of a transcription factor are fused to two different proteins. If the proteins interact with each other, the transcription factor can allow reporter gene expression.

A)DNA binding, activation
B)DNA binding, inhibition
C)regulation, activation
D)fish, bait
E)upper, lower

Question 53

A solvent passes through a column and is collected as it drips out of the bottom of the column into a series of tubes; each of these tubes is called ____________.

A)an elutant
B)a fractal
C)a diluent
D)a fraction
E)a digest

Question 54

Which technique can be used for molecular weight (mass)determinations in proteins?

A)X- ray diffraction
B)chromatofocusing
C)diethylaminoethyl (DEAE)cellulose chromatography
D)affinity chromatography
E)SDS-PAGE

Question 55

What is required in order to study a protein's fine structure or function?

A)It must be isolated in a relatively pure state.
B)It must be observed in a light microscope.
C)It must be denatured.
D)It must be enzymatically degraded.
E)It must be fixed.

Question 56

Why have frozen-hydrated particles largely replaced negatively stained specimens for high resolution cryo-EM studies?

A)Frozen-hydrated particles are more likely to generate artifacts.
B)Frozen-hydrated particles are much less likely to generate artifacts.
C)Frozen-hydrated particles take positively charged stains more efficiently
D)Frozen-hydrated particles are much better suited for the study of external features within the particle's structure.

Question 57

The first fully human antibody has been manufactured using bacteriophage rather than hybridomas; it is approved for rheumatoid arthritis treatment and is called _________.

A)Phagoma
B)Humira
C)Humana
D)Humantibody
E)Amana

Question 58

Electron cryomicroscopy can be used to cause membrane proteins to become closely packed at very low temperatures into two-dimensional crystalline arrays within the plane of a membrane. The structures of such proteins are then determined from combined, high-resolution electron microscope images of many different protein molecules taken at various angles. This process is called __________.

A)cryopreservation
B)electron crystallography
C)cryohistology
D)electron cryocrystallography
E)proton microscopy

Question 59

For each protein, there is a pH at which negative and positive charges are equal. This pH is referred to as the ___________.

A)pH point
B)neutralization point
C)isometric point
D)isoelectric point
E)isotonic point

Question 60

Which of the following is most likely to elute first from a gel filtration column if each of them is essentially globular?

A)a 250 kilodalton protein
B)a 120 kilodalton protein
C)a chromate ion
D)a 12 kilodalton protein
E)an 80 kilodalton protein

Question 61

How big are the sites recognized by most restriction enzymes?

A)4 - 6 nucleotides
B)6 - 8 nucleotides
C)2 - 4 nucleotides
D)8 - 10 nucleotides
E)10- 12 nucleotides

Question 62

How sensitive is gel electrophoresis when it is used to separate DNA?

A)It can separate fragments of DNA that differ grossly in size.
B)It can separate really big DNAs from very small DNAs.
C)It can separate DNAs that differ by hundreds of nucleotides.
D)It can separate DNA molecules that vary in length by only a single nucleotide.
E)It can separate DNA molecules that vary in length by five or more nucleotides.

Question 63

How can a researcher visualize the DNA fragments separated in an electrophoresis gel?

A)using a labeled probe with a sequence complementary to the desired DNA fragment
B)staining with ethidium bromide
C)staining with potassium chloride
D)using labeled antibodies
E)staining with Coomassie Blue

Question 64

A small, circular, double-stranded DNA molecule that is separate from the main bacterial chromosome is called a ___________.

A)circuloid
B)nucleoid
C)plasmid
D)palmid
E)plummet

Question 65

Under what circumstances will a component in a solution or a suspension sediment through a centrifugal field?

A)if it has a greater density than the surrounding medium
B)if it has a lower density than the surrounding medium
C)if it is wet
D)if the surrounding medium is denser than the component
E)if the component and the surrounding medium have equal density

Question 66

During the gene cloning procedure, what is the purpose of inserting genes into a bacterium that give it resistance to antibiotics?

A)Antibiotic resistance allows researchers to select for those cells that contain a plasmid.
B)Antibiotic resistance allows researchers to kill those cells that contain a recombinant plasmid.
C)Antibiotic resistance increases the generation time of the bacteria.
D)Antibiotic resistance decreases bacterial generation time.

Question 67

Nowadays, what is the most common method for synthesizing double-stranded molecules of DNA for use in experimental procedures?

A)by insertion into bacterial cells
B)by insertion into bacteriophage
C)by automated synthesis of two single stranded DNAs, followed by hybridization
D)in quartz cuvettes
E)by insertion into fungi

Question 68

Nucleic acid hybridization techniques are based on the observation that ______________.

A)DNA can be very long
B)two single-stranded nucleic acid molecules of complementary base sequence can form a double-stranded hybrid
C)DNA molecules are very hydrophobic
D)two single-stranded nucleic acid molecules of any base sequence can form a double-stranded hybrid
E)two double-stranded nucleic acid molecules of complementary base sequence can form a double-stranded hybrid

Question 69

Which of the following is a technique used to encourage bacteria to take up DNA from the surrounding culture medium?

A)pretreatment of bacteria with a brief heat shock, followed by exposure to Ca²⁺ ions
B)pretreatment of bacteria with Cu²⁺ ions, followed by a brief heat shock
C)pretreatment of bacteria with Ca²⁺ ions, followed by a brief heat shock
D)pretreatment of bacteria with Ca²⁺ ions, followed by a brief cold shock
E)pretreatment of bacteria with a brief heat shock, followed by exposure to Mg²⁺ ions

Question 70

What is the term used to describe a piece of DNA containing sequences derived from more than one organism?

A)combinational DNA
B)recombinant DNA
C)combined DNA
D)cloned DNA
E)recreational DNA

Question 71

What is the name of the procedure in which single-stranded DNA molecules are separated by electrophoresis, immobilized on a nitrocellulose filter and then hybridized with labeled, single-stranded DNA probes?

A)Southern blot
B)Northern blot
C)Western blot
D)Southwestern blot
E)Eastern blot

Question 72

Why does the S value alone not provide a measure of molecular mass?

A)It is too difficult to measure.
B)The speed with which a particle travels through a liquid column is not uniform.
C)The velocity at which a particle moves through a liquid column depends on a number of factors, including shape.
D)The velocity of movement accelerates as the particle approaches the bottom of the tube.
E)The velocity of movement slows up as the particle approaches the top of the tube.

Question 73

What does the change in field direction in pulsed field electrophoresis accomplish?

A)It makes the DNA molecules move faster.
B)It causes the DNA molecules to reorient themselves during their migration.
C)It causes the DNA molecules to denature.
D)It causes the DNA molecules to renature.
E)It causes the stain to adhere better to the DNA molecules.

Question 74

In what medium are small RNAs or DNAs of a few hundred nucleotides typically separated through electrophoresis?

A)agarose
B)polyacrylamide
C)cellulose
D)paper
E)dextran

Question 75

How are probes labeled with a radioactive isotope detected?

A)autoradiography
B)fluorescence
C)by changing colors
D)SEM
E)TEM

Question 76

When DNA molecules from two different organisms are incubated together, some duplexes are formed by DNA strands from the two species. What indicates that such duplexes are less stable than those between strands from the same organism?

A)Heterogeneous duplexes melt at lower temperatures than homogeneous duplexes.
B)Heterogeneous duplexes melt at higher temperatures than homogeneous duplexes.
C)Heterogeneous duplexes are degraded faster.
D)Heterogeneous duplexes are degraded more slowly.
E)There is no difference in stability between homogeneous and heterogeneous duplexes.

Question 77

How are double-stranded hybrids released from hydroxylapatite columns?

A)by increasing elution buffer concentration
B)by decreasing elution buffer concentration
C)by increasing pH
D)by decreasing pH
E)by increasing sucrose concentration

Question 78

A term to describe short, single-stranded nucleic acid molecules is _________.

A)mininucleotides
B)micronucleotides
C)polynucleotides
D)oligonucleotides

Question 79

What is the technique for producing millions of copies of recombinant DNA with a specific DNA sequence in a short period of time from one or a few initial copies?

A)DNA reproduction
B)DNA cloning
C)DNA replication
D)DNA transcription
E)DNA copying

Question 80

How do DNA molecules place themselves in a CsCl equilibrium gradient?

A)They continuously move toward the bottom of the gradient.
B)They stop momentarily at the point in the gradient equaling their buoyant density.
C)They continuously move toward the top of the gradient.
D)They stop permanently at the point in the gradient equaling their buoyant density.
E)All DNA molecules localize at the same point in the gradient.