Question 1

Polyacrylamide gel properties can be altered by adjusting T and C values. What are T and C in this context?

Accepted Answer

A)   Temperature of polymerization and concentration of acrylamide
B)   Time of polymerization and number of cytosines in the nucleic acid to be separated
C)   Total concentration of acrylamide plus cross-linker and percent cross-linker
D)   TEMED concentration and concentration of APS used for polymerization C

Question 2

A molecular biologist is to separate and analyze a mixture of nucleic acids that are about 100,000 bp in size. Which of the following methods will yield the best results?

Accepted Answer

A)   Capillary electrophoresis
B)   Rotating gel electrophoresis
C)   Polyacrylamide gel electrophoresis
D)   Traditional agarose gel electrophoresis B

Question 3

Which of the following are used to make wells in a solidifying gel into which samples are loaded?

Accepted Answer

A)   Brushes
B)   Combs
C)   Picks
D)   Shovels B

Question 4

A molecular technologist has run a vertical gel. While analyzing the gel, the technologist notices that the bands in the outer lanes did not run as far as similar-sized bands in the inner lanes, so the bands look like a smile on the gel. What is the explanation for this?

Accepted Answer

A)   Samples were loaded into the inner wells first and got a head start moving down the gel.
B)   A larger volume of sample was loaded into the outer wells so that they ran slower.
C)   The electrodes in the middle of the gel were working better than at the edges of the gel.
D)   The temperature across the gel was not constant, so the inner wells were warmer.

Question 5

Nucleic acids migrate toward which pole in electrophoresis?

Accepted Answer

A)   Cathode
B)   Anode

Question 6

The matrix in capillary electrophoresis through which nucleic acids pass is:

Accepted Answer

A)   Silica
B)   Agarose
C)   Agarobiose
D)   Optimized polymer

Question 7

A very limited amount of nucleic acid, 500-1500 bp in size, is to be analyzed in a short time (same day) with the results available immediately. Which of the following electrophoresis procedures will satisfy those conditions?

Accepted Answer

A)   Capillary electrophoresis
B)   Pulse-field gel electrophoresis
C)   Field inversion gel electrophoresis
D)   Contour-clamped homogeneous electric field

Question 8

The positive pole in electrophoresis is indicated by which color?

Accepted Answer

A)   Red
B)   Black
C)   Green
D)   White

Question 9

Which is an important property of gel running buffers?

Accepted Answer

A)   Solubility at low temperature
B)   Ability to maintain constant pH
C)   Capacity to heat up quickly
D)   High ultraviolet light absorption

Question 10

Which of the following molecules is added to an electrophoresis buffer for the purpose of denaturing DNA?

Accepted Answer

A)   Ethylenediaminetetraacetic acid
B)   Polyacrylamide
C)   Formamide
D)   Tris borate

Question 11

Which of the following molecules polymerize to form a support medium through which nucleic acids move?

Accepted Answer

A)   Ethidium bromide
B)   Ethylenediaminetetraacetic acid
C)   Sodium dodecyl sulfate
D)   Polyacrylamide

Question 12

Which of the following can be used to detect the location of DNA bands in a gel after electrophoresis?

Accepted Answer

A)   SYBR Green
B)   Xylene cyanol green
C)   Bromophenol blue
D)   Hematoxylin

Question 13

Which of the following properties is true for ethidium bromide?

Accepted Answer

A)   Emits green light when excited at 200 nm
B)   Level of detection is 5 pg of DNA
C)   Intercalates between nitrogen bases
D)   Has no background fluorescence in agarose

Question 14

The functions of which of the following include carrying the current and protecting the sample nucleic acids during electrophoresis?

Accepted Answer

A)   Glycerol
B)   Formaldehyde
C)   Ammonium persulfate
D)   Tris borate EDTA

Question 15

What concentration of agarose should be used for optimal separation of DNA fragments of 100, 250, and 350 bp in length?

Accepted Answer

A)   0.5%
B)   0.7%
C)   2.0%
D)   12.0%

Question 16

What is one reason that polyacrylamide gels have higher resolution than agarose gels for small fragments?

Accepted Answer

A)   Agarose polymer spaces are bigger than those of polyacrylamide.
B)   Agarose polymers are very fragile.
C)   Agarose won't separate molecules over a certain size.
D)   Agarose is a synthetic polymer in which sieving properties can be precisely controlled.

Question 17

Which of the following molecules will migrate fastest in capillary electrophoresis?

Accepted Answer

A)   Large and positively charged
B)   Small and positively charged
C)   Large and negatively charged
D)   Small and negatively charged

Question 18

What is an advantage of agarose over polyacrylamide gels?

Accepted Answer

A)   Agarose is more stable than polyacrylamide.
B)   Agarose monomers are not toxic.
C)   Acrylamide takes a long time to polymerize.
D)   Polyacrylamide gels must be used immediately after polymerization.

Question 19

To monitor the progress of electrophoresis, which of the following is added to a sample that does not associate with DNA and runs ahead of the smallest fragments in the sample?

Accepted Answer

A)   Ethidium bromide
B)   Acrylamide
C)   Bromophenol blue
D)   SYBR Green

Question 20

As compared with traditional slab gel electrophoresis, which of the following is not an advantage of capillary electrophoresis?

Accepted Answer

A)   Analyzes smaller amounts of samples
B)   Ability to run more than one sample together
C)   Cost of instrumentation and labels
D)   Real-time sample detection and analysis

Exam 5: Resolution and Detection of Nucleic Acids