Practice Exam 2 Questions and Guaranteed
Solutions.
Only one statement about PCR is wrong. Which one is it?
a. During 95oC step of PCR all double stranded DNA fragments are separated (melted)
into single stranded fragments.
b. During 60oC step of PCR primers anneal to target sequences.
c. During 72oC step of PCR Taq polymerase starts to extend primers.
d. All synthesized fragments after PCR have the same length.
e. After 30 cycles of PCR the theoretical amplification rate is 230 = 1,073,741,824,
however in reality it is lower simply because there is not enough building blocks
(nucleotides) in the tube. - >d. All synthesized fragments after PCR have the same length.
Only one statement about COVID PCR test is incorrect. Which one is it?
For the COVID PCR test ...
a. Swabs from areas most likely containing virus particles has to be obtained.
b. Virus RNA has to be extracted and converted into DNA by reverse transcriptase.
c. DNA has to be extracted and purified.
d. Primers complementary to the virus DNA has to be used.
e. If virus nucleic acid sequence is present it will block the amplification by PCR. - >e. If
virus nucleic acid sequence is present it will block the amplification by PCR.
What is the correct (only one) statement about Huntington's disease PCR test?
a. The Huntington's PCR amplicons from a particular patient have always the same size.
b. The test is positive if PCR product is detected.
c. Huntington's disease is recessive.
d. The amount of CTG repeats detected by PCR is above 37 for the unaffected person.
, e. Two amplicons often detected during the Huntington's disease PCR test are the result
of human sexual reproduction. - >e. Two amplicons often detected during the
Huntington's disease PCR test are the result of human sexual reproduction.
What is the incorrect (only one) statement?
a. During allele-discriminating Real-time PCR...
Three oligonucleotides are used.
b. Both 5' to 3' and 3' to 5' exonuclease activities of Taq polymerase are being utilized.
c. One oligonucleotide is destroyed for each amplicon molecule synthesized.
d. Reporter and quencher are separated by Taq polymerase during amplicon synthesis.
e. The yield of the PCR amplicon is measured after 30 cycles of PCR. - >e. The yield of the
PCR amplicon is measured after 30 cycles of PCR.
If during the COVID PCR test the threshold amplification level is reached on 28th cycle
instead of 23th cycle, than...
a. The individual has 5 times higher COVID titer (amount of COVID DNA).
b. The individual has 5 times lower COVID titer (amount of COVID DNA).
c. The individual has 32 times higher COVID titer (amount of COVID DNA).
d. The individual has 32 times lower COVID titer (amount of COVID DNA).
e. The individual does not have COVID. - >d. The individual has 32 times lower COVID
titer (amount of COVID DNA).
Only one statement about Sanger DNA sequencing is incorrect. Which one is it?
For Sanger sequencing...
a. To read the sequence of one DNA fragment one needs to do four separate DNA
polymerase reactions.
b. In each reaction the synthesis is terminated by a specific dideoxynucleotide.
c. The amount of fragments generated in each sequencing reaction is proportional to the
amount of letters causing termination.
d. Each reaction mix contains deoxy and dideoxy nucleotides.
Solutions.
Only one statement about PCR is wrong. Which one is it?
a. During 95oC step of PCR all double stranded DNA fragments are separated (melted)
into single stranded fragments.
b. During 60oC step of PCR primers anneal to target sequences.
c. During 72oC step of PCR Taq polymerase starts to extend primers.
d. All synthesized fragments after PCR have the same length.
e. After 30 cycles of PCR the theoretical amplification rate is 230 = 1,073,741,824,
however in reality it is lower simply because there is not enough building blocks
(nucleotides) in the tube. - >d. All synthesized fragments after PCR have the same length.
Only one statement about COVID PCR test is incorrect. Which one is it?
For the COVID PCR test ...
a. Swabs from areas most likely containing virus particles has to be obtained.
b. Virus RNA has to be extracted and converted into DNA by reverse transcriptase.
c. DNA has to be extracted and purified.
d. Primers complementary to the virus DNA has to be used.
e. If virus nucleic acid sequence is present it will block the amplification by PCR. - >e. If
virus nucleic acid sequence is present it will block the amplification by PCR.
What is the correct (only one) statement about Huntington's disease PCR test?
a. The Huntington's PCR amplicons from a particular patient have always the same size.
b. The test is positive if PCR product is detected.
c. Huntington's disease is recessive.
d. The amount of CTG repeats detected by PCR is above 37 for the unaffected person.
, e. Two amplicons often detected during the Huntington's disease PCR test are the result
of human sexual reproduction. - >e. Two amplicons often detected during the
Huntington's disease PCR test are the result of human sexual reproduction.
What is the incorrect (only one) statement?
a. During allele-discriminating Real-time PCR...
Three oligonucleotides are used.
b. Both 5' to 3' and 3' to 5' exonuclease activities of Taq polymerase are being utilized.
c. One oligonucleotide is destroyed for each amplicon molecule synthesized.
d. Reporter and quencher are separated by Taq polymerase during amplicon synthesis.
e. The yield of the PCR amplicon is measured after 30 cycles of PCR. - >e. The yield of the
PCR amplicon is measured after 30 cycles of PCR.
If during the COVID PCR test the threshold amplification level is reached on 28th cycle
instead of 23th cycle, than...
a. The individual has 5 times higher COVID titer (amount of COVID DNA).
b. The individual has 5 times lower COVID titer (amount of COVID DNA).
c. The individual has 32 times higher COVID titer (amount of COVID DNA).
d. The individual has 32 times lower COVID titer (amount of COVID DNA).
e. The individual does not have COVID. - >d. The individual has 32 times lower COVID
titer (amount of COVID DNA).
Only one statement about Sanger DNA sequencing is incorrect. Which one is it?
For Sanger sequencing...
a. To read the sequence of one DNA fragment one needs to do four separate DNA
polymerase reactions.
b. In each reaction the synthesis is terminated by a specific dideoxynucleotide.
c. The amount of fragments generated in each sequencing reaction is proportional to the
amount of letters causing termination.
d. Each reaction mix contains deoxy and dideoxy nucleotides.
