BIO 348- EXAM #2
Approximately how often does DNA polymerase make an error during DNA replication?
Choose one:
A. once per 100 nucleotides added to the growing DNA chain
B. once per 1000 nucleotides added to the growing DNA chain
C. once per 1 million nucleotides added to the growing DNA chain
D. once per 10 million nucleotides added to the growing DNA chain
E. never, because DNA polymerase is always self-correcting - ANS-D. once per 10 million
nucleotides added to the growing DNA chain
DNA polymerase makes only about one error in every 107 nucleotide pairs it copies. That
means that an error happens once per 10 million nucleotides added to the growing DNA chain.
What is the main function of the TATA-binding protein? - ANS-To promote initiation of
transcription
TATA-binding protein bends the DNA, which signals assembly of the transcription complex,
increasing transcription initiation.
Which of the following events occur when TATA-binding protein binds to the DNA?
Choose one or more:
A. An eight-stranded β-sheet domain of the TATA-binding protein lies on the DNA helix.
B. The DNA backbone is kinked nearly 90 degrees.
C. Binding leads to assembly of the rest of the transcription complex at the initiation site.
D. Four α helices separate the two strands of DNA. - ANS-A. An eight-stranded β-sheet domain
of the TATA-binding protein lies on the DNA helix.B. The DNA backbone is kinked nearly 90
degrees.C. Binding leads to assembly of the rest of the transcription complex at the initiation
site.
The TATA-binding protein β-sheet domain induces a kink in the DNA, leading to assembly of the
transcription complex and initiation of transcription.
Which of the following statements is supported by the information in this image and is consistent
with your knowledge regarding genomic architecture in prokaryotes and eukaryotes?
Choose one:
A. The eukaryotic cell must have a nuclear spliceosome to remove introns from DNA.
B. The prokaryotic cell must have a cytoplasmic spliceosome to remove introns from RNA.
C. The eukaryotic cell must have a nuclear spliceosome to remove introns from RNA.
,D. The eukaryotic cell must have a cytoplasmic spliceosome to remove introns from RNA.
E. The prokaryotic cell must have a nuclear spliceosome to remove introns from DNA. - ANS-C.
The eukaryotic cell must have a nuclear spliceosome to remove introns from RNA.
Eukaryotic genes contain introns, which must be removed from the RNA transcript in the
nucleus before translation can occur in the cytosol. Bacterial genes lack introns, so their RNA
transcripts do not need splicing.
This image represents the process of ____________, which is an event that occurs
___________ in gene expression.
choices for the first blank:
transcription
translation
choices for second blank:
early
late - ANS-Transcription, early
Transcription is when DNA is used as a template for RNA synthesis. The enzyme RNA
polymerase catalyzes transcription.
Transcription happens much earlier in the genetic expression cascade because to translate an
mRNA to make protein, the mRNA must be created first.
Where or when does RNA capping at the 5' end of the transcript take place? - ANS-As an RNA
is being transcribed
Capping is the addition of a modified guanine nucleotide to the 5' end of an RNA molecule and
occurs almost immediately after transcription has begun.
Which of the following statements is false?
Choose one:
A. The longer the lifetime of an mRNA, the more protein it can produce.
B. Many eukaryotic mRNAs have a longer lifetime than bacterial mRNAs.
C. The lifetime of a eukaryotic mRNA is controlled in part by nucleotide sequences in the mRNA
itself.
D. In a eukaryotic mRNA, the poly-A tail promotes degradation of the molecule. - ANS-D. In a
eukaryotic mRNA, the poly-A tail promotes degradation of the molecule.
In a eukaryotic mRNA, the poly-A tail promotes longer-term stability of the molecule, not
degradation.
, What structure is responsible for selecting and transporting only properly processed eukaryotic
mRNAs into the cytoplasm?Choose one:
A. SnRNPs
B. nuclear pore complex
C. Spliceosome
D. RNA polymerase
E. ribosomes - ANS-B. nuclear pore complex
Properly processed mature mRNAs will bind a collection of proteins that aid in their delivery to
and through the nuclear pore complex.
In eukaryotes, which parts of a gene are transcribed into RNA?
Choose one:
A. introns and exons
B. the protein-coding region only
C. introns only
D. exons only - ANS-A. Introns and exons
In eukaryotes, the introns and the exons of a gene are transcribed into RNA. Introns are spliced
out by the activity of the spliceosome, leaving only exons in the mature mRNA.
Determine whether the following statement is true or false: In bacteria, most protein-coding
genes lack introns.
This statement is ______
true
false - ANS-True
Introns are commonly found in eukaryotic genes but are not part of prokaryotic genetic
organization. In eukaryotes, these introns must be removed before translation can take place.
Which of the following does not increase the stability of eukaryotic mRNAs?
Choose one:
A. a 5'-end cap
B. an intron
C. a poly-A tail - ANS-B. An intron
What is true of eukaryotic mRNAs?
Choose one:
A. They are processed only after being released by the polymerase.
B. They are translated by enzymes that ride on the phosphorylated tail of RNA polymerase II.
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