PCB 3063 EXAM 4 REVIEW QUESTIONS & ANSWERS
When a eukaryotic mRNA is hybridized to the complementary DNA, loops of un-
hybridized DNA are seen. These loops ____________.
A. correspond to noncoding regions of the gene
B. demonstrate that genes and proteins are not colinear.
C. represent introns that are removed
D. All of the above. - Answers :D. All of the above.
What is the most likely result from mutating a prokaryotic Shine-Dalgarno sequence?
A. The first amino acid of the translated protein would be changed.
B. The mRNA would be less stable.
C. The ribosome would not be able to bind to the mRNA.
D. None of the above. Prokaryotes do not have a Shine-Dalgarno sequence. - Answers
:C. The ribosome would not be able to bind to the mRNA.
Which is NOT true of ribosomes?
A. They are one of the most abundant molecular complexes of both eukaryotic and
prokaryotic cells.
B. They are made up entirely of ribosomal RNA molecules.
C. They contain a small subunit and a large subunit.
D. RNAs undergo extensive processing before assembly into the ribosome. - Answers
:B. They are made up entirely of ribosomal RNA molecules.
Any given DNA sequence has _____ possible reading frames, and the correct one is
set by a(n) ______________.
A. 2; termination codon
B. 4; initiation codon
C. 3; initiation codon
D. 3; termination codon
E. 2; initiation codon - Answers :C. 3; initiation codon
What is the final component of the initiation complex to be added?
A. large subunit of the ribosome
B. small subunit of the ribosome
C.tmRNA
D. initiator tRNA
E. GTP - Answers :A. large subunit of the ribosome
Which of the following is NOT a correct description of how translation differs between
bacteria and eukaryotic cells?
A. In bacterial cells, transcription and translation can occur simultaneously, whereas in
eukaryotic cells these processes occur in different cellular locations.
, B. In prokaryotes, the small ribosomal subunit associates with the mRNA at the Shine-
Dalgarno sequence, whereas in eukaryotes the small ribosomal subunit first associates
with the 5' cap of the mRNA.
C. In prokaryotes the initiator codon is recognized by met-tRNA, whereas in eukaryotes
the initiator codon is recognized by fmet-tRNA.
D. Eukaryotic ribosomes are larger and have an additional rRNA that bacterial
ribosomes lack. - Answers :C. In prokaryotes the initiator codon is recognized by met-
tRNA, whereas in eukaryotes the initiator codon is recognized by fmet-tRNA.
The kind of gene whose product interacts with other nucleotide sequences to affect their
transcription or translation is a ______.
A. constitutive gene
B. regulatory gene
C. structural gene
D. protein-coding gene - Answers :B. regulatory gene
A typical operon contains several regions. In which region does a regulator protein
bind?
A. structural genes
B. promoter
C. operator
D. regulatory promoter - Answers :C. operator
For a(n) __________ operon, transcription normally does NOT take place, and it is kept
off by a(n) _________.
A. inducible; activator
B. inducible; repressor
C. repressible; activator
D. repressible; repressor - Answers :B. inducible; repressor
Low levels of glucose lead to all of the following, EXCEPT that __________.
A. cAMP levels increase
B. permease levels increase
C. β-galactosidase levels increase
D. lac operon is activated
E. CAP-cAMP loses its affinity to DNA - Answers :E. CAP-cAMP loses its affinity to DNA
Suppose that a mutant form of GAL80 protein lacks the domain that binds to GAL4
protein. Yeast cells with this mutant GAL80 will ______.
A. never activate the genes needed for galactose metabolism
B. always repress the genes needed for galactose metabolism even in the presence of
galactose
C. always activate the genes needed for galactose metabolism even in the absence of
galactose
When a eukaryotic mRNA is hybridized to the complementary DNA, loops of un-
hybridized DNA are seen. These loops ____________.
A. correspond to noncoding regions of the gene
B. demonstrate that genes and proteins are not colinear.
C. represent introns that are removed
D. All of the above. - Answers :D. All of the above.
What is the most likely result from mutating a prokaryotic Shine-Dalgarno sequence?
A. The first amino acid of the translated protein would be changed.
B. The mRNA would be less stable.
C. The ribosome would not be able to bind to the mRNA.
D. None of the above. Prokaryotes do not have a Shine-Dalgarno sequence. - Answers
:C. The ribosome would not be able to bind to the mRNA.
Which is NOT true of ribosomes?
A. They are one of the most abundant molecular complexes of both eukaryotic and
prokaryotic cells.
B. They are made up entirely of ribosomal RNA molecules.
C. They contain a small subunit and a large subunit.
D. RNAs undergo extensive processing before assembly into the ribosome. - Answers
:B. They are made up entirely of ribosomal RNA molecules.
Any given DNA sequence has _____ possible reading frames, and the correct one is
set by a(n) ______________.
A. 2; termination codon
B. 4; initiation codon
C. 3; initiation codon
D. 3; termination codon
E. 2; initiation codon - Answers :C. 3; initiation codon
What is the final component of the initiation complex to be added?
A. large subunit of the ribosome
B. small subunit of the ribosome
C.tmRNA
D. initiator tRNA
E. GTP - Answers :A. large subunit of the ribosome
Which of the following is NOT a correct description of how translation differs between
bacteria and eukaryotic cells?
A. In bacterial cells, transcription and translation can occur simultaneously, whereas in
eukaryotic cells these processes occur in different cellular locations.
, B. In prokaryotes, the small ribosomal subunit associates with the mRNA at the Shine-
Dalgarno sequence, whereas in eukaryotes the small ribosomal subunit first associates
with the 5' cap of the mRNA.
C. In prokaryotes the initiator codon is recognized by met-tRNA, whereas in eukaryotes
the initiator codon is recognized by fmet-tRNA.
D. Eukaryotic ribosomes are larger and have an additional rRNA that bacterial
ribosomes lack. - Answers :C. In prokaryotes the initiator codon is recognized by met-
tRNA, whereas in eukaryotes the initiator codon is recognized by fmet-tRNA.
The kind of gene whose product interacts with other nucleotide sequences to affect their
transcription or translation is a ______.
A. constitutive gene
B. regulatory gene
C. structural gene
D. protein-coding gene - Answers :B. regulatory gene
A typical operon contains several regions. In which region does a regulator protein
bind?
A. structural genes
B. promoter
C. operator
D. regulatory promoter - Answers :C. operator
For a(n) __________ operon, transcription normally does NOT take place, and it is kept
off by a(n) _________.
A. inducible; activator
B. inducible; repressor
C. repressible; activator
D. repressible; repressor - Answers :B. inducible; repressor
Low levels of glucose lead to all of the following, EXCEPT that __________.
A. cAMP levels increase
B. permease levels increase
C. β-galactosidase levels increase
D. lac operon is activated
E. CAP-cAMP loses its affinity to DNA - Answers :E. CAP-cAMP loses its affinity to DNA
Suppose that a mutant form of GAL80 protein lacks the domain that binds to GAL4
protein. Yeast cells with this mutant GAL80 will ______.
A. never activate the genes needed for galactose metabolism
B. always repress the genes needed for galactose metabolism even in the presence of
galactose
C. always activate the genes needed for galactose metabolism even in the absence of
galactose
