BIO 353 - Cell Biology Exam 2 Version B,
BIO353 Exam 2 (100 points) LATEST
SOLUTIONS FREQUENTLY TESTED
A(n) _________________ is a segment of DNA that contains one or more structural
genes that are all under the control of a single promoter and are transcribed into
one polycistronic mRNA.
a. Operator
b. Mediator
c. Operon
d. Riboswitch - ANSWER>>A. Operon
If a prokaryotic gene is regulated by a weak promoter, high levels of
transcription can only take place if
A. Activator proteins cause the chromatin to transition from a condensed form to
a more open form, allowing better access for RNA polymerase.
B. Activator proteins help stabilize interactions between RNA polymerase and the
promoter.
C. Activator proteins methylate the promoter allowing RNA polymerase to bind
more tightly.
D. Activator proteins bind to repressor proteins, preventing the repressor from
blocking RNA polymerase. - ANSWER>>B. Activator proteins help stabilize
interactions between RNA polymerase and the promoter
Where do repressor proteins bind to DNA in prokaryotic cells?
A. Operator
B. Enhancer
C. Activator Binding Site
D. Silencer - ANSWER>>A. Operator
Which one of the following represents a co-repressor in prokaryotes?
,A. Arabinose that binds to the AraC activator
B. Lactose that binds to the lac repressor
C. Guanine that causes the formation of a termination loop
D. Tryptophan that binds to the trp repressor - ANSWER>>D. Tryptophan that
binds to the trp repressor
Which one of the following conditions best describes what is likely occurring in
the image above?
A. Glucose levels are high, Lactose levels are low
B. Glucose levels are high, Lactose levels are high
C. Glucose levels are low, lactose levels are low
D. Glucose levels are low, lactose levels are high - ANSWER>>A. Glucose levels
are high, Lactose levels are low
Which one of the following is a way by which eukaryotic activator proteins
regulate transcription?
A. They replace general transcription factors.
B. They cause a conformational change in the mRNA as it is being transcribed.
C. They recruit histone modifying enzymes.
D. They methylate DNA. - ANSWER>>C. They recruit histone modifying enzymes.
What is an enhancer?
A. A binding site for eukaryotic activators
B. A binding site for general transcription factors
C. A protein complex that stimulates DNA looping
D. A transcription factor that increases gene expression - ANSWER>>A. A
binding site for eukaryotic activators
In general, what is the effect of DNA methylation?
A. Increased transcription
B. Decreased transcription
C. Increased translation
, D. Decreased translation - ANSWER>>B. Decreased transcription
_________ is a short, non-coding RNA molecule that functions in post-
transcriptional regulation of gene expression.
a. miRNA
b. siRNA
c. RNAi
d. RISC - ANSWER>>a. miRNA
_________ is a short, non-coding RNA molecule which is made from double-
stranded viral RNA and is used to target and destroy viral genomic material.
a. miRNA
b. siRNA
c. RNAi
d. RISC - ANSWER>>b. siRNA
How might antisense RNA affect translation?
A. It can interfere with ribosome function by blocking the P site.
B. It can enhance ribosome binding by modifying binding sites.
C. It can prevent identification of the start codon by the ribosome.
D. It can interfere with the normal secondary structure of the mRNA molecule. -
ANSWER>>C. It can prevent identification of the start codon by the ribosome.
Genes that are constitutively expressed are ________________.
A. Only located in heterochromatin
B. Induced by methylation
C. Never transcribed
D. Always transcribed - ANSWER>>D. Always transcribed
How are eukaryotic activators able to affect transcription when their binding sites
are far from the promoter?
A. By binding to their binding site and sliding towards RNA polymerase
BIO353 Exam 2 (100 points) LATEST
SOLUTIONS FREQUENTLY TESTED
A(n) _________________ is a segment of DNA that contains one or more structural
genes that are all under the control of a single promoter and are transcribed into
one polycistronic mRNA.
a. Operator
b. Mediator
c. Operon
d. Riboswitch - ANSWER>>A. Operon
If a prokaryotic gene is regulated by a weak promoter, high levels of
transcription can only take place if
A. Activator proteins cause the chromatin to transition from a condensed form to
a more open form, allowing better access for RNA polymerase.
B. Activator proteins help stabilize interactions between RNA polymerase and the
promoter.
C. Activator proteins methylate the promoter allowing RNA polymerase to bind
more tightly.
D. Activator proteins bind to repressor proteins, preventing the repressor from
blocking RNA polymerase. - ANSWER>>B. Activator proteins help stabilize
interactions between RNA polymerase and the promoter
Where do repressor proteins bind to DNA in prokaryotic cells?
A. Operator
B. Enhancer
C. Activator Binding Site
D. Silencer - ANSWER>>A. Operator
Which one of the following represents a co-repressor in prokaryotes?
,A. Arabinose that binds to the AraC activator
B. Lactose that binds to the lac repressor
C. Guanine that causes the formation of a termination loop
D. Tryptophan that binds to the trp repressor - ANSWER>>D. Tryptophan that
binds to the trp repressor
Which one of the following conditions best describes what is likely occurring in
the image above?
A. Glucose levels are high, Lactose levels are low
B. Glucose levels are high, Lactose levels are high
C. Glucose levels are low, lactose levels are low
D. Glucose levels are low, lactose levels are high - ANSWER>>A. Glucose levels
are high, Lactose levels are low
Which one of the following is a way by which eukaryotic activator proteins
regulate transcription?
A. They replace general transcription factors.
B. They cause a conformational change in the mRNA as it is being transcribed.
C. They recruit histone modifying enzymes.
D. They methylate DNA. - ANSWER>>C. They recruit histone modifying enzymes.
What is an enhancer?
A. A binding site for eukaryotic activators
B. A binding site for general transcription factors
C. A protein complex that stimulates DNA looping
D. A transcription factor that increases gene expression - ANSWER>>A. A
binding site for eukaryotic activators
In general, what is the effect of DNA methylation?
A. Increased transcription
B. Decreased transcription
C. Increased translation
, D. Decreased translation - ANSWER>>B. Decreased transcription
_________ is a short, non-coding RNA molecule that functions in post-
transcriptional regulation of gene expression.
a. miRNA
b. siRNA
c. RNAi
d. RISC - ANSWER>>a. miRNA
_________ is a short, non-coding RNA molecule which is made from double-
stranded viral RNA and is used to target and destroy viral genomic material.
a. miRNA
b. siRNA
c. RNAi
d. RISC - ANSWER>>b. siRNA
How might antisense RNA affect translation?
A. It can interfere with ribosome function by blocking the P site.
B. It can enhance ribosome binding by modifying binding sites.
C. It can prevent identification of the start codon by the ribosome.
D. It can interfere with the normal secondary structure of the mRNA molecule. -
ANSWER>>C. It can prevent identification of the start codon by the ribosome.
Genes that are constitutively expressed are ________________.
A. Only located in heterochromatin
B. Induced by methylation
C. Never transcribed
D. Always transcribed - ANSWER>>D. Always transcribed
How are eukaryotic activators able to affect transcription when their binding sites
are far from the promoter?
A. By binding to their binding site and sliding towards RNA polymerase
