Deck 11: Electrophoresis

Question 1

The isoelectric point (pI)of a protein is the pH at which the protein:

A) has a positive charge.
B) has a negative charge.
C) has no net charge.
D) migrates best in electrophoresis.

Answer 1

has no net charge.

Question 2

The main advantage of capillary electrophoresis over standard gel electrophoresis is:

A) the increased amount of time required for separation.
B) the small sample size required.
C) more efficient heat dissipation for better separation.
D) the ability to use a variety of buffers in the system.

Answer 2

more efficient heat dissipation for better separation.

Question 3

What would the concentration of albumin be if the total protein value was 8.5 g/dL and the densitometer measured the albumin fraction as 55% of the total?

A) Albumin values cannot be calculated using densitometry.
B) 15.4 g/dL
C) 0.065 g/dL
D) 4.68 g/dL

Answer 3

4.68 g/dL

Question 4

If the viscosity of the support medium used in a protein electrophoresis system is too high (thick),the rate of migration will:

A) increase.
B) decrease.
C) not be affected.

Question 5

Endosmosis:

A) can be eliminated from an electrophoretic system if a charged gel is used.
B) is the movement of solvent along with highly hydrated ions to produce the driving force in capillary electrophoresis.
C) is the movement of water toward the center of an electrophoresis gel or strip to replace water lost by evaporation.
D) is a type of electrophoresis where separation is conducted in fluid channels.

Question 6

You have just set up the morning protein electrophoresis.When you return 45 minutes later,you stain the gel and notice that the bands did not migrate very far from the point of application.What is the likely explanation?

A) A chemical reaction occurred between the buffer and all samples.
B) The current or voltage on the power supply was set too low.
C) Too much sample had been applied to the gel.
D) The electrophoresis chamber was not connected to a power supply.

Question 7

What stains are used to stain a serum protein electrophoresis gel?

A) Coomassie Blue and ethidium bromide
B) Oil Red O and Amido Black
C) Amido Black and Coomassie Brilliant Blue
D) Crystal Violet and Sudan Black

Question 8

The process of transferring the electrophoresed DNA fragments out of a gel and onto a special nylon paper is referred to as:

A) Southern blotting.
B) Northern blotting.
C) Western blotting.
D) hybridization.

Question 9

In electrophoresis,the best support medium to use because it is thermostable,strong,transparent,and eliminates endosmosis due to the lack of a charge is:

A) agar.
B) agarose.
C) cellulose acetate.
D) polyacrylamide.

Question 10

A separation technique that can detect proteins in a complex mixture with the use of antibodies directed against a protein of interest is:

A) Northern blotting.
B) Western blotting.
C) capillary electrophoresis.
D) electrokinetic chromatography.

Question 11

A type of electrophoresis that provides increased resolution in protein separation by allowing the protein to migrate to a point where the protein's charge becomes zero and its migration stops is _____ electrophoresis.

A) capillary
B) isoelectric focusing
C) disc
D) zone

Question 12

The component of an electrophoresis system that carries the applied current and establishes the pH at which electrophoresis is performed is the:

A) power supply.
B) buffer.
C) support media.
D) stain.

Question 13

In an electrophoresis system,the _____ is the negative electrode.

A) anode
B) optode
C) diode
D) cathode

Question 14

If the viscosity of the support medium used in a protein electrophoresis system is too high (thick),the migration rate will:

A) increase.
B) decrease.
C) not be affected.

Question 15

You are examining a protein electrophoresis pattern and notice an unusual band at the starting point of the electropherogram that is not present in the normal control.If the patient were healthy,what is the most likely cause of the unusual banding pattern?

A) A plasma sample was probably applied instead of serum.
B) The buffer used in the electrophoresis had the wrong pH.
C) An inappropriate support medium was used for the electrophoresis.
D) The patient likely has a genetic abnormality.

Question 16

The theory of electrophoresis states that:

A) components of a sample mixture are separated by differential distribution of analytes between stationary and mobile phases.
B) the exquisite specificity and high affinity of antibodies for specific antigens,coupled with the unique ability of antibodies to cross-link antigens,allows for the identification and quantification of specific substances.
C) the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light.
D) ionized chemical species having an electrical charge move toward either the cathode (negative electrode)or the anode (positive electrode).

Question 17

In capillary electrophoresis,hydrodynamic sample injection:

A) involves sample injection into the capillary by applying a positive pressure to the sample inlet.
B) is best for analytes that have a higher electrophoretic mobility.
C) involves sample injection into the capillary by applying a voltage.
D) is sometimes considered to be a "biased" type of sample injection.

Question 18

What is the importance of the ionic strength of the buffer used in gel electrophoresis?

A) A heat-labile protein will become denatured if the ionic strength of the buffer is too high.
B) Increased ionic strength will lead to a backward electrophoretic pattern.
C) No migration will occur if a buffer's ionic strength is too high.
D) Staining of the protein fractions will not occur if the ionic strength in the buffer is too high.

Question 19

On a serum protein electrophoresis,if the albumin band appears distorted and large,the likely cause is:

A) pH of electrophoretic buffer incorrect.
B) instrument not connected.
C) sample overload.
D) inappropriate support material used.

Question 20

Upon receiving a serum sample for protein electrophoresis,which you perform using agarose gel,you note that the specimen is hemolyzed.How would hemolysis affect the banding pattern of this type of electrophoresis?

A) There would be an increased $\alpha$ ₁-globulin band.
B) There would be an increased $\beta$ -globulin band.
C) There would be an increase in the $\gamma$ -globulin bands.
D) There would be no effect on any of the protein bands.