Question

A random multiple choice question abiut the topic, Dideoxy DNA Sequencing of Sanger?

Answer 1

1. Why don't we see the template strand on the gel?
   • The denaturing step and the urea in the gel destroyed it
   • The template strand lacks radioactively/fluorescently labeled ddNTP
   • The template strand is too large to appear as a band on the gel
2. All of the following are disadvantages of the Sanger method except:
   • It requires PCR amplification prior to sequencing
   • It is limited by the resolution of polyacrylamide gel electrophoresis
   • It is expensive
   • It has low accuracy compared to most other methods
3. Why must DNA be amplified prior to sequencing?
   • Just to be safe in case DNA is destroyed during the denaturation step
   • So we have a higher chance of ssDNA coming in contact with DNA polymerase
   • More DNA molecules in a single band on the polyacrylamide gel makes it easier to read the gel
   • It increases the probability of getting all possible chain terminated strands
4. Given a template strand: 5' AGTATAGTGTTAGGTGTCATAGTACAAGG 3', which of the following could be used as a DNA primer?
   • 5' CCTTGTACTATG 3'
   • 5' TAACACTATACT 3'
   • 5' CATAGTACAAGG 3'
   • 5' AGTATAGTGTTA 3'
5. If we have 2 dATPs, 1 dCTP, 1 ddCTP, and 2 ddGTPs in one reaction tube, which of the following strands could be produced from a sample containing the following template strand: 5' GCTTGGCTTAACCAGATATTCCACTG 3' with the following primer: 5' CAGTGGAATATCTGGTT 3'?
   • 5' CAGTGGAATATCTGGTTAAG 3'
   • 5' CAGTGGAATATCTGGTTAAGCC 3'
   • 5' CAGTGGAATATCTGGTTAAGCCAA 3'
   • Just #1 & #2
   • #1, #2, and #3 are all possible
6. In gel electrophoresis, DNA migrates to the _______ end, which is the ________.
   • positive, cathode
   • postive, anode
   • negative, cathode
   • negative, anode
7. Based on this figure, the most likely error is:
   • The scientist forgot to add dNTPs to one of the reaction tubes
   • The scientist did not fluorescently/radioactively label one of the ddNTPs
   • The scientist mixed up the cathode and the anode during gel electrophoresis
   • The scientist did not denature the DNA strands
   • The scientist added two different ddNTPs to one of the reaction tubes
   • The scientist forgot to add ddNTP to one of the reaction tubes
8. Based on this figure, which lane contains the shortest DNA strand? (assume the anode is at the bottom)
   • Lane A
   • Lane T
   • Lane C
   • Lane G
9. Based on this figure, we can deduce what DNA sequence? (assume the anode is at the bottom)
   • 5' CACTCAATGTCATGCTGCAT 3'
   • 5' TACGTCGTACTGTAACTCAC 3'
   • 5' GAGTGAATGTGATGGTGGAT 3'
   • 5' CACTCAATCTCATCCTCCAT 3'
   • The scientist's error renders it impossible to determine the DNA sequence
10. If you wish to sequence a long strand of DNA in one round of reactions, you should:
    • Increase the ddNTP/dNTP ratio
    • Decrease the ddNTP/dNTP ratio
    • Use a shorter DNA primer
    • None of the above

Note- answers in bold.