Exam 6: Electrophoresis and chromatography

Question 1

pH of buffer in most electrophoresis methods

Answer 1

8.6 (serum proteins will be negatively charged anions and migrate towards the anode)

Question 2

Ohm’s law

Answer 2

E = I x R
E = voltage in volts, I = current in amps, R = resistance in Ohms

Question 3

Electrophoresis

Answer 3

The migration of charged particles in an electrical field

Question 4

Migration (electrophoresis)

Answer 4

The distance the molecules move from the point of application

Question 5

The rate of migration in electrophoresis is dependent upon

Answer 5

Net electric charge of the molecule
Size and shape
Electric field strength
Support medium
Temperature

Question 6

Electrophoretic mobility is directly proportional to

Answer 6

net charge

Question 7

Electrophoretic mobility is indirectly proportional to

Answer 7

size

Question 8

A basic electrophoretic system consists of what components?

Answer 8

Support medium
Buffer
Chamber with electrodes
Power supply

Question 9

Factors affecting separation in electrophoresis

Answer 9

pH
Ionic strength
Voltage and current
Support media

Question 10

Ampholytes/zwitterions

Answer 10

Proteins that are amphoretic in nature (can be either positively or negatively charged)

Question 11

Amphoretic

Answer 11

Can be positively or negatively charged

Question 12

Function of a buffer in electrophoresis

Answer 12

Maintains pH

Conducts electric current

Question 13

Most commonly used support media for electrophoresis, and its advantages

Answer 13

Agarose gel

Has few ionizable groups (less interference due to electroendosmosis) and low protein affinity

Question 14

Wick flow

Answer 14

Evaporation of buffer in the middle draws up more buffer from the ends of the gel
Controlled by keeping lid on system and cooling temperature

Question 15

Electroendosmosis

Answer 15

Flow of buffer ions and solvent in opposite direction of protein migration
Buffer cations flow toward cathode, along with gamma globulins (cathodic migration)
Minimized by using media with few ionizable groups and low protein affinity (agarose gel)

Question 16

Commonly used stains in electrophoresis

Answer 16

Coomassie brilliant blue and Amido black

Question 17

Principle of chromatography

Answer 17

Separation of compounds based upon interaction with two phases (stationary and mobile phase)

Question 18

Clinical uses of chromatography

Answer 18

Toxicology, amino acids, glycohemoglobin

Question 19

Ion exchange chromatography

Answer 19

Solute mixtures are separated by virtue of the magnitude and charge of ionic species

Question 20

Cation exchange chromatography

Answer 20

The stationary phase carries a negative charge and thus selects cations from the sample

Question 21

Anion exchange chromatography

Answer 21

The stationary phase carries a positive charge and thus selects anions from the sample

Question 22

Steric exclusion chromatography

Answer 22

Stationary phase contains small pores that allow separation based on size and shape

Question 23

Adsorption chromatography

Answer 23

Solid stationary phase has adsorptive (sticky) sites to capture compounds

Question 24

Partition chromatography

Answer 24

Separation is based on polarity (one phase is polar, the other is non-polar)

Question 25

The most selective type of chromatography

Answer 25

Affinity chromatography

Question 26

The most common type of detector in use in automated chromatography methods

Answer 26

Flame ionization detectors

Question 27

During gas chromatography, where does separation occur?

Answer 27

Column

Question 28

What basic component present in liquid chromatography, is missing in gas chromatography?

Answer 28

Pump

Question 29

What chromatography principle of separation is based on polarity?

Answer 29

Partition