Chapter 18

Question 1

How does a light microscope work?

Answer 1

Uses the refraction of light rays to magnify an image

Question 2

What does a condenser do?

Answer 2

directs light towards a specimen

Question 3

What does the objective lens do?

Answer 3

Collects light from the specimen

Question 4

What does the ocular lens do?

Answer 4

forms enlarged, virtual image

Question 5

What is the numerical aperture?

Answer 5

measure of the light-gathering qualities of the lens

Question 6

What does the limit of resolution depend on?

Answer 6

wavelength of light

Question 7

What is a bright field microscope and what is it best suited for?

Answer 7

light that illuminates the specimen is seen as a bright background; it is suited for specimens of high contrast such as stained tissues

Question 8

What is phase-contrast microscopy?

Answer 8

Makes highly transparent objects more visible by converting differences in the refractive index of some parts of the specimen into differences of light intensity.

Question 9

What does differential interference contrast (DIC) optics do>?

Answer 9

gives image 3-d quality

Question 10

What are fluorochromes?

Answer 10

compounds that release visible light upon absorption of UV rays

Question 11

How is fluorescence microscopy used?

Answer 11

GFP from jelly fish can be used to recombine with and follow genes of interest

Question 12

What is fluorescence resonance energy transfer?

Answer 12

Uses fluorochromes to measure changes in distance between labeled cellular components

Question 13

What is a transmission electron microscope?

Answer 13

Use electrons instead of light to form images, resulting in image displays 100-200 fold increase in resolution compared to light microscope

Question 14

What does differential centrifugation do?

Answer 14

facilitates isolation of particular organelles in bulk quantity

Question 15

What is a scanning electron microscope?

Answer 15

form images from electrons bounced off the specimens surface

Question 16

How is protein purification measured?

Answer 16

As an increase in specific activity of a protein

Question 17

The best way to precipitate a protein is:

Answer 17

High ionic strength, like ammonium sulfate

Question 18

What is ion-exchange chromatography? and what are its components?

Answer 18

1) uses ionic charge as a basis for purification
2) DEAE-cellulose (+ charged) anion exchanger
3) CM- cellulos (- charged) cation exchanger

Question 19

What is gel filtration chromatography?

Answer 19

separation of three globular proteins having different molecular masses. Among proteins of similar basic shape, larger molecules are eluted before smaller ones.

Question 20

What is affinity chromatography?

Answer 20

isolates one protein from a mixture using a specific ligand

Question 21

What technique is based on DNA hybridization?

Answer 21

Southern blot

Question 22

What technique is based on RNA-DNA hybridization?

Answer 22

Northern blot

Question 23

What technique is based on protein hybridization?

Answer 23

Western blot

Question 24

What type of chromatography is most selective?

Answer 24

Affinity chromatography

Question 25

What method is used to resolve protein structures?

Answer 25

X-ray crystallography

Question 26

What method allows you to look at protein-protein interactions?

Answer 26

yeast two-hybrid system

Question 27

What cells are used in knockout mice?

Answer 27

ES cells

Question 28

What is a polymerase chain reaction?

Answer 28

A technique used to amplify specific DNA fragments. Repeated cycles of denaturation, DNA replication, and cooling doubles the amount of DNA during each cycle making it useful for research

Question 29

What is microscopic resolution?

Answer 29

The ability to distinguish between two points at a microscopic level.

Question 30

What is two-dimensional gel electrophoresis?

Answer 30

It separates proteins on the basis of both isoelectric focusing and molecular weight. It is ideal for detecting changes in the proteins in a cell under different conditions

Question 31

What are some applications for PCR?

Answer 31

1) Amplifying DNA for cloning or analysis 2) Testing for specific DNA sequences 3) Comparing DNA molecules 4) Quantifying DNA or RNA templates

Question 32

What are cDNA libraries based on?

Answer 32

DNA copies of an RNA library

Question 33

What is transduction?

Answer 33

DNA incorporation into the genome of a non-replicating human virus

Question 34

What is transfection?

Answer 34

DNA introduced into cell cultures

Question 35

What is a transgene?

Answer 35

The gene whose role is being investigated after transfection

Question 36

What is STORM?

Answer 36

Stochastic optical reconstruction microscropy, allows for the localization of a single fluorescent molecule within a resolution of <20 nm. Live cell

Question 37

What is autoradiography?

Answer 37

Technique where a particular isotope is located. A particle emitted from a radioactive atom activates a photographic emulsion. Location determined by positions of the overlying silver grains in photographic emulsion.

Question 38

What is the best cell culture to observe cell-cell interactions?

Answer 38

3D culture

Question 39

What is x-ray crystallography?

Answer 39

uses crystals, diffraction pattern provides information about protein structure.

Question 40

What can be used to determine the degree of similarity between two samples?

Answer 40

hybridization