BioChem 385 exam 4 questions and
answers graded A+
If 15N DNA (heavy) replicated using conservative replication in 14N (light) media, the outcome
would be different than semi-conservative replication, and in this case, the two daughter DNA
double strands would be ______________after one generation. - correct answer ✔✔Heavy only
for one daughter DNA and light for the other daughter DNA
Prokaryotic and eukaryotic DNA polymerases rarely make mismatched base pairs because
____________. - correct answer ✔✔The active site does not fit mismatches well
Why do helicase and gyrase need to work together to keep the replication fork moving forward?
- correct answer ✔✔Helicase unwinds DNA and gyrase relieves the torsional strain created by
the unwinding.
The Tus-Ter complex terminates E. coli DNA synthesis by ____________. - correct answer
✔✔blocking the opening of the DNA helix at the fork by helicase.
The Ames test is designed to identify mutation rates using a strategy based on ___________. -
correct answer ✔✔The frequency of new mutations that compensate for an existing mutation.
Individuals with mutations of BRCA have increased incidence of cancer because of
their___________. - correct answer ✔✔decreased ability to repair double-strand DNA breaks
A Holliday junction can best be defined as a region of ________________. - correct answer
✔✔a quadruplex DNA structure
, Lysogeny by bacteriophages causes what results in the host DNA? - correct answer
✔✔integration of virus DNA into host DNA
How are RNA tertiary structures different from protein tertiary structures? - correct answer
✔✔RNA adopts multiple structures, whereas protein structures are restricted.
Long noncoding RNA (lncRNA) is generated from _____________. - correct answer ✔✔the
transcription of genomic DNA.
How do bacterial sigma factor proteins promote RNA synthesis? - correct answer ✔✔They
recruit RNA polymerase to specific sequences at the 5' end of genes.
In which direction is mRNA synthesized by prokaryotic and eukaryotic RNA polymerases? -
correct answer ✔✔The mRNA is synthesized with 5' to 3' phosphodiester linkages.
The spliceosome ___________. - correct answer ✔✔resembles group II introns in its
mechanism and product.
A common chemical modification found in RNA is __________________. - correct answer
✔✔methylation of nucleotide bases in tRNA
Identify one way in which RNA splicing can give rise to multiple mRNA transcripts from a gene
containing 3 exons and 2 introns. - correct answer ✔✔Splicing between the 3' end of exon 1 and
5' end of exon 3.
The enzyme responsible for generating siRNA from double strand RNA is ____________. -
correct answer ✔✔Dicer
In an iteration of the Nirenberg-Leder experiment to assign triplet codons to specific amino
acids, radioactively labeled aminoacyl-tRNA with the anticodon of 3'-CUG-5' was retained on
answers graded A+
If 15N DNA (heavy) replicated using conservative replication in 14N (light) media, the outcome
would be different than semi-conservative replication, and in this case, the two daughter DNA
double strands would be ______________after one generation. - correct answer ✔✔Heavy only
for one daughter DNA and light for the other daughter DNA
Prokaryotic and eukaryotic DNA polymerases rarely make mismatched base pairs because
____________. - correct answer ✔✔The active site does not fit mismatches well
Why do helicase and gyrase need to work together to keep the replication fork moving forward?
- correct answer ✔✔Helicase unwinds DNA and gyrase relieves the torsional strain created by
the unwinding.
The Tus-Ter complex terminates E. coli DNA synthesis by ____________. - correct answer
✔✔blocking the opening of the DNA helix at the fork by helicase.
The Ames test is designed to identify mutation rates using a strategy based on ___________. -
correct answer ✔✔The frequency of new mutations that compensate for an existing mutation.
Individuals with mutations of BRCA have increased incidence of cancer because of
their___________. - correct answer ✔✔decreased ability to repair double-strand DNA breaks
A Holliday junction can best be defined as a region of ________________. - correct answer
✔✔a quadruplex DNA structure
, Lysogeny by bacteriophages causes what results in the host DNA? - correct answer
✔✔integration of virus DNA into host DNA
How are RNA tertiary structures different from protein tertiary structures? - correct answer
✔✔RNA adopts multiple structures, whereas protein structures are restricted.
Long noncoding RNA (lncRNA) is generated from _____________. - correct answer ✔✔the
transcription of genomic DNA.
How do bacterial sigma factor proteins promote RNA synthesis? - correct answer ✔✔They
recruit RNA polymerase to specific sequences at the 5' end of genes.
In which direction is mRNA synthesized by prokaryotic and eukaryotic RNA polymerases? -
correct answer ✔✔The mRNA is synthesized with 5' to 3' phosphodiester linkages.
The spliceosome ___________. - correct answer ✔✔resembles group II introns in its
mechanism and product.
A common chemical modification found in RNA is __________________. - correct answer
✔✔methylation of nucleotide bases in tRNA
Identify one way in which RNA splicing can give rise to multiple mRNA transcripts from a gene
containing 3 exons and 2 introns. - correct answer ✔✔Splicing between the 3' end of exon 1 and
5' end of exon 3.
The enzyme responsible for generating siRNA from double strand RNA is ____________. -
correct answer ✔✔Dicer
In an iteration of the Nirenberg-Leder experiment to assign triplet codons to specific amino
acids, radioactively labeled aminoacyl-tRNA with the anticodon of 3'-CUG-5' was retained on
