MOLECULAR DIAGNOSTICS EXAM #2 QUESTIONS AND ANSWERS
The 260 nm/280 nm ratio for isolated DNA was determined to be 1:2. What should be done next with
this sample? - (answer)Reprecipitate the DNA to remove excess protein.
PolyT oligomers bound to a matrix resin column will selectively isolate which of the following? -
(answer)Messenger RNA
What is the yield of DNA from a sample with concentration of 280 g/mL and a volume of 0.5 mL? -
(answer)140 μg
In what way is fluorometry more accurate than spectrophotometry? - (answer)Using specific stains,
fluorometry only detects intact double-stranded DNA.
What is the concentration of RNA whereby a 1:10 dilution has an absorbance reading of 0.675 at 260
nm? - (answer)270 μg/mL
Isolated DNA has an absorbance at 260 nm of 0.268 and an absorbance at 280 nm of 0.191. What is the
260 nm/280 nm ratio? - (answer)1:4
What is the concentration of DNA whereby a 1:100 dilution has an absorbance reading of 0.015 at 260
nm? - (answer)75 μg/mL
DNA is isolated from a clinical sample. The absorbance at 260 nm is 0.489, and the absorbance at 280
nm is 0.257. Is this sample of sufficient quality for use in subsequent analyses? - (answer)Yes
What is the yield of RNA from the sample with concentration of 450 g/mL and a volume of 0.3 mL? -
(answer)135 μg
A DNA-specific dye that is used in fluorometry procedures to measure DNA concentration is: -
(answer)Hoechst 33258
Which of the following is the first step in DNA isolation from cells in a clinical sample? - (answer)Lysis of
cells
, MOLECULAR DIAGNOSTICS EXAM #2 QUESTIONS AND ANSWERS
In inorganic DNA isolation, or "salting out" procedures, in the presence of low-pH and high-salt
concentrations, which intracellular component precipitates out of solution? - (answer)Protein
Which of the following is used to optimize yield of nucleic acid by precipitation or column purification? -
(answer)Carrier molecules
The most abundant form of RNA in all cells is: - (answer)Ribosomal
Which of the following will yield the best DNA preparation? - (answer)Fresh blood
Which whole blood fraction is the most abundant source of genomic DNA? - (answer)Buffy coat
Phenol/chloroform and an aqueous solution will form what type of mixture? - (answer)Emulsion
In organic DNA extraction methods, the DNA is found in which fraction? - (answer)Upper aqueous
Which of the following will not inhibit RNAses? - (answer)Tris buffer
DNA, after separation from other cellular constituents, is precipitated in which of the following? -
(answer)Isopropanol
In organic isolation of RNA procedures, guanidinium isothiocyanate is added to: - (answer)Inhibit RNAses
Nucleic acid concentration can be assessed relatively simply and quickly by which of the following
procedures? - (answer)Electrophoresis
When measuring the concentration of RNA by spectrophotometry at 260 nm, the absorbance reading is
multiplied by the dilution and a conversion factor of: - (answer)40
The 260 nm/280 nm ratio for isolated DNA was determined to be 1:2. What should be done next with
this sample? - (answer)Reprecipitate the DNA to remove excess protein.
PolyT oligomers bound to a matrix resin column will selectively isolate which of the following? -
(answer)Messenger RNA
What is the yield of DNA from a sample with concentration of 280 g/mL and a volume of 0.5 mL? -
(answer)140 μg
In what way is fluorometry more accurate than spectrophotometry? - (answer)Using specific stains,
fluorometry only detects intact double-stranded DNA.
What is the concentration of RNA whereby a 1:10 dilution has an absorbance reading of 0.675 at 260
nm? - (answer)270 μg/mL
Isolated DNA has an absorbance at 260 nm of 0.268 and an absorbance at 280 nm of 0.191. What is the
260 nm/280 nm ratio? - (answer)1:4
What is the concentration of DNA whereby a 1:100 dilution has an absorbance reading of 0.015 at 260
nm? - (answer)75 μg/mL
DNA is isolated from a clinical sample. The absorbance at 260 nm is 0.489, and the absorbance at 280
nm is 0.257. Is this sample of sufficient quality for use in subsequent analyses? - (answer)Yes
What is the yield of RNA from the sample with concentration of 450 g/mL and a volume of 0.3 mL? -
(answer)135 μg
A DNA-specific dye that is used in fluorometry procedures to measure DNA concentration is: -
(answer)Hoechst 33258
Which of the following is the first step in DNA isolation from cells in a clinical sample? - (answer)Lysis of
cells
, MOLECULAR DIAGNOSTICS EXAM #2 QUESTIONS AND ANSWERS
In inorganic DNA isolation, or "salting out" procedures, in the presence of low-pH and high-salt
concentrations, which intracellular component precipitates out of solution? - (answer)Protein
Which of the following is used to optimize yield of nucleic acid by precipitation or column purification? -
(answer)Carrier molecules
The most abundant form of RNA in all cells is: - (answer)Ribosomal
Which of the following will yield the best DNA preparation? - (answer)Fresh blood
Which whole blood fraction is the most abundant source of genomic DNA? - (answer)Buffy coat
Phenol/chloroform and an aqueous solution will form what type of mixture? - (answer)Emulsion
In organic DNA extraction methods, the DNA is found in which fraction? - (answer)Upper aqueous
Which of the following will not inhibit RNAses? - (answer)Tris buffer
DNA, after separation from other cellular constituents, is precipitated in which of the following? -
(answer)Isopropanol
In organic isolation of RNA procedures, guanidinium isothiocyanate is added to: - (answer)Inhibit RNAses
Nucleic acid concentration can be assessed relatively simply and quickly by which of the following
procedures? - (answer)Electrophoresis
When measuring the concentration of RNA by spectrophotometry at 260 nm, the absorbance reading is
multiplied by the dilution and a conversion factor of: - (answer)40
