MOLECULAR DIAGNOSTICS FINAL
TEST QUESTIONS AND ANSWERS
Calculate the DNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-767.5 ug/mL
Calculate the DNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-860 ug/mL
Calculate the DNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-440 ug/mL
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.307 - ANSWER-767.5 ug
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-383.8 ug
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-430 ug
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-220 ug
Based on the A260/A280 ratio, is the preparation below suitable for further use? If
not, what is contaminating the DNA?
OD260 = 0.419
OD280 = 0.230 - ANSWER-Ratio = 1.82
This DNA sample is suitable for use.
Based on the A260/A280 ratio, is the preparation below suitable for further use? If
not, what is contaminating the DNA?
OD260 = 0.258
OD280 = 0.225 - ANSWER-Ratio = 1.15
This DNA sample is not suitable for use due to protein contamination.
Based on the A260/A280 ratio, is the preparation below suitable for further use? If
not, what is contaminating the DNA?
OD260 = 0.398
OD280 = 0.174 - ANSWER-Ratio = 2.29
This DNA may be suitable for use if RNA does not interfere with the subsequent
assay.
After agarose gel electrophoresis, a 0.5-microgram aliquot of DNA isolated from a
bacterial culture produced only a faint smear at the bottom of the gel lane. Is this an
acceptable DNA sample? - ANSWER-This amount of DNA should produce a bright
, band/smear near the top of the gel lane. This DNA is probably degraded and is
therefore unacceptable.
Compare and contrast the measurement of DNA concentration by
spectrophotometry with analysis by fluorometry with regard to staining requirements
and accuracy. - ANSWER-Spectrophotometry requires no DNA staining. Fluorometry
requires staining of DNA to generate a fluorescent signal. Fluorometry may be more
accurate than spectrophotometry because double-stranded DNA must be intact to
stain and generate a signal, whereas single nucleotides will absorb light in
spectrophotometry.
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.307 - ANSWER-1,228
ug/mL
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-614 ug/mL
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-688 ug/mL
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-352 ug/mL
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.307 - ANSWER-614 ug
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-307 ug
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-344 ug
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-1.76 ug
An RNA preparation has the following absorbance readings:
A260 = 0.208
A280 = 0.096
Is this RNA preparation satisfactory for use? - ANSWER-Ratio = 2.17
This RNA preparation is satisfactory for use.
A blood sample was held at room temperature for 5 days before being processed for
RNA isolation. Will this sample likely yield optimal RNA? - ANSWER-This sample will
not yield optimal RNA due to degradation and changes in gene expression at room
temperature.
Name three factors that will affect the yield of RNA from a paraffin-embedded tissue
sample. - ANSWER-Isolation of RNA from fixed tissue is affected by the type of
fixative used, the age/length of the storage of the tissue, and the preliminary
TEST QUESTIONS AND ANSWERS
Calculate the DNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-767.5 ug/mL
Calculate the DNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-860 ug/mL
Calculate the DNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-440 ug/mL
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.307 - ANSWER-767.5 ug
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-383.8 ug
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-430 ug
If the volume of the DNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-220 ug
Based on the A260/A280 ratio, is the preparation below suitable for further use? If
not, what is contaminating the DNA?
OD260 = 0.419
OD280 = 0.230 - ANSWER-Ratio = 1.82
This DNA sample is suitable for use.
Based on the A260/A280 ratio, is the preparation below suitable for further use? If
not, what is contaminating the DNA?
OD260 = 0.258
OD280 = 0.225 - ANSWER-Ratio = 1.15
This DNA sample is not suitable for use due to protein contamination.
Based on the A260/A280 ratio, is the preparation below suitable for further use? If
not, what is contaminating the DNA?
OD260 = 0.398
OD280 = 0.174 - ANSWER-Ratio = 2.29
This DNA may be suitable for use if RNA does not interfere with the subsequent
assay.
After agarose gel electrophoresis, a 0.5-microgram aliquot of DNA isolated from a
bacterial culture produced only a faint smear at the bottom of the gel lane. Is this an
acceptable DNA sample? - ANSWER-This amount of DNA should produce a bright
, band/smear near the top of the gel lane. This DNA is probably degraded and is
therefore unacceptable.
Compare and contrast the measurement of DNA concentration by
spectrophotometry with analysis by fluorometry with regard to staining requirements
and accuracy. - ANSWER-Spectrophotometry requires no DNA staining. Fluorometry
requires staining of DNA to generate a fluorescent signal. Fluorometry may be more
accurate than spectrophotometry because double-stranded DNA must be intact to
stain and generate a signal, whereas single nucleotides will absorb light in
spectrophotometry.
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.307 - ANSWER-1,228
ug/mL
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-614 ug/mL
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-688 ug/mL
Calculate the RNA concentration in ug/mL from the following information:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-352 ug/mL
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.307 - ANSWER-614 ug
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:50 dilution = 0.307 - ANSWER-307 ug
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.172 - ANSWER-344 ug
If the volume of the RNA solutions is 0.5 mL, calculate the yield for the following:
Absorbance reading at 260 nm from a 1:100 dilution = 0.088 - ANSWER-1.76 ug
An RNA preparation has the following absorbance readings:
A260 = 0.208
A280 = 0.096
Is this RNA preparation satisfactory for use? - ANSWER-Ratio = 2.17
This RNA preparation is satisfactory for use.
A blood sample was held at room temperature for 5 days before being processed for
RNA isolation. Will this sample likely yield optimal RNA? - ANSWER-This sample will
not yield optimal RNA due to degradation and changes in gene expression at room
temperature.
Name three factors that will affect the yield of RNA from a paraffin-embedded tissue
sample. - ANSWER-Isolation of RNA from fixed tissue is affected by the type of
fixative used, the age/length of the storage of the tissue, and the preliminary
