Question 1

What are the coding segments of a stretch of eukaryotic DNA called?

Accepted Answer

A)  introns
B)  exons
C)  codons
D)  replicons
E)  transposons

Question 2

The anticodon of a particular tRNA molecule is

Accepted Answer

A)  complementary to the corresponding mRNA codon.
B)  complementary to the corresponding triplet in rRNA.
C)  the part of tRNA that bonds to a specific amino acid.
D)  changeable, depending on the amino acid that attaches to the tRNA.
E)  catalytic, making the tRNA a ribozyme.

Question 3

Figure 17.4 
-The tRNA shown in Figure 17.4 has its 3' end projecting beyond its 5' end. What will occur at this 3' end?

Accepted Answer

A)  The codon and anticodon complement one another.
B)  The amino acid binds covalently.
C)  The excess nucleotides (ACC
A)  will be cleaved off at the ribosome.
D)  The small and large subunits of the ribosome will attach to it.
E)  The 5' cap of the mRNA will become covalently bound.

Question 4

The following questions refer to Figure 17.1, a simple metabolic pathway:

-If A, B, and C are all required for growth, a strain that is mutant for the gene encoding enzyme A would be able to grow on which of the following media?

Accepted Answer

A)  minimal medium
B)  minimal medium supplemented with nutrient "A" only
C)  minimal medium supplemented with nutrient "B" only
D)  minimal medium supplemented with nutrient "C" only
E)  minimal medium supplemented with nutrients "A" and "C"

Question 5

RNA polymerase moves in which direction along the DNA?

Accepted Answer

A)  3' → 5' along the template strand
B)  3' → 5' along the coding (sense) strand
C)  5' → 3' along the template strand
D)  3' → 5' along the coding strand
E)  5' → 3' along the double-stranded DNA

Question 6

An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?

Accepted Answer

A)  tRNA will not form a cloverleaf.
B)  The nearby stem end will pair improperly.
C)  The amino acid methionine will not bind.
D)  The anticodon will not bind with the mRNA codon.
E)  The aminoacylsynthetase will not be formed.

Question 7

Which of the following is not True of RNA processing?

Accepted Answer

A)  Exons are cut out before mRNA leaves the nucleus.
B)  Nucleotides may be added at both ends of the RNA.
C)  Ribozymes may function in RNA splicing.
D)  RNA splicing can be catalyzed by spliceosomes.
E)  A primary transcript is often much longer than the final RNA molecule that leaves the nucleus.

Question 8

Which of these is the function of a poly (A) signal sequence?

Accepted Answer

A)  It adds the poly (
A)  tail to the 3' end of the mRNA.
B)  It codes for a sequence in eukaryotic transcripts that signals enzymatic cleavage ~10-35 nucleotides away.
C)  It allows the 3' end of the mRNA to attach to the ribosome.
D)  It is a sequence that codes for the hydrolysis of the RNA polymerase.
E)  It adds a 7-methylguanosine cap to the 3' end of the mRNA.

Question 9

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?

Accepted Answer

A)  The tRNA that was in the A site moves into the P site.
B)  The tRNA that was in the P site moves into the A site.
C)  The tRNA that was in the A site moves to the E site and is released.
D)  The tRNA that was in the A site departs from the ribosome via a tunnel.
E)  The polypeptide enters the E site.

Question 10

Which of the following statements best describes the termination of transcription in prokaryotes?

Accepted Answer

A)  RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase.
B)  RNA polymerase transcribes through the terminator sequence, causing the polymerase to fall off the DNA and release the transcript.
C)  RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript.
D)  Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome.
E)  RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

Question 11

A frameshift mutation could result from

Accepted Answer

A)  a base insertion only.
B)  a base deletion only.
C)  a base substitution only.
D)  deletion of three consecutive bases.
E)  either an insertion or a deletion of a base.

Question 12

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

Accepted Answer

A)  3' UCA 5'.
B)  3' UGA 5'.
C)  5' TCA 3'.
D)  3'ACU 5'.
E)  either UCA or TCA, depending on wobble in the first base.

Question 13

When does translation begin in prokaryotic cells?

Accepted Answer

A)  after a transcription initiation complex has been formed
B)  as soon as transcription has begun
C)  after the 5' caps are converted to mRNA
D)  once the pre-mRNA has been converted to mRNA
E)  as soon as the DNA introns are removed from the template

Question 14

Which of the following help(s) to stabilize mRNA by inhibiting its degradation?

Accepted Answer

A)  TATA box
B)  spliceosomes
C)  5' cap and poly (
A)  tail
D)  introns
E)  RNA polymerase

Question 15

RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism of such sigma switching?

Accepted Answer

A)  It might allow the transcription process to vary from one cell to another.
B)  It might allow the polymerase to recognize different promoters under certain environmental conditions.
C)  It could allow the polymerase to react differently to each stop codon.
D)  It could allow ribosomal subunits to assemble at faster rates.
E)  It could alter the rate of translation and of exon splicing.

Question 16

If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides?

Accepted Answer

A)  1
B)  2
C)  3
D)  4
E)  12

Question 17

Each eukaryotic mRNA, even after post-transcriptional modification, includes 5' and 3' UTRs. Which are these?

Accepted Answer

A)  the cap and tail at each end of the mRNA
B)  the untranslated regions at either end of the coding sequence
C)  the U attachment sites for the tRNAs
D)  the U translation sites that signal the beginning of translation
E)  the U - A pairs that are found in high frequency at the ends

Question 18

A mutation in which of the following parts of a gene is likely to be most damaging to a cell?

Accepted Answer

A)  intron
B)  exon
C)  5' UTR
D)  3' UTR
E)  All would be equally damaging.

Question 19

Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?

Accepted Answer

A)  a base substitution
B)  a base deletion near the start of a gene
C)  a base deletion near the end of the coding sequence, but not in the terminator codon
D)  deletion of three bases near the start of the coding sequence, but not in the initiator codon
E)  a base insertion near the end of the coding sequence, but not in the terminator codon

Question 20

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that

Accepted Answer

A)  none of the proteins in the cell will contain phenylalanine.
B)  proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
C)  the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.
D)  the ribosome will skip a codon every time a UUU is encountered.
E)  None of the above will occur; the cell will recognize the error and destroy the tRNA.

Exam 17: From Gene to Protein

Which of the following help(s) to stabilize mRNA by inhibiting its degradation?

Correct AnswerverifiedShow Answer

What are the coding segments of a stretch of eukaryotic DNA called?

Correct AnswerverifiedShow Answer

If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides?

Correct AnswerverifiedShow Answer

RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism of such sigma switching?

Correct AnswerverifiedShow Answer

An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following hypotheses describes the most likely result?

Correct AnswerverifiedShow Answer

Each eukaryotic mRNA, even after post-transcriptional modification, includes 5' and 3' UTRs. Which are these?

Correct AnswerverifiedShow Answer

Which of the following statements best describes the termination of transcription in prokaryotes?

Correct AnswerverifiedShow Answer

Which of these is the function of a poly (A) signal sequence?

Correct AnswerverifiedShow Answer

Figure 17.4 -The tRNA shown in Figure 17.4 has its 3' end projecting beyond its 5' end. What will occur at this 3' end?

Correct AnswerverifiedShow Answer

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is

Correct AnswerverifiedShow Answer

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for the cell will be that

Correct AnswerverifiedShow Answer

Which point mutation would be most likely to have a catastrophic effect on the functioning of a protein?

Correct AnswerverifiedShow Answer

When does translation begin in prokaryotic cells?

Correct AnswerverifiedShow Answer

The following questions refer to Figure 17.1, a simple metabolic pathway: -If A, B, and C are all required for growth, a strain that is mutant for the gene encoding enzyme A would be able to grow on which of the following media?

Correct AnswerverifiedShow Answer

Which of the following is not True of RNA processing?

Correct AnswerverifiedShow Answer

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?

Correct AnswerverifiedShow Answer

The anticodon of a particular tRNA molecule is

Correct AnswerverifiedShow Answer

A mutation in which of the following parts of a gene is likely to be most damaging to a cell?

Correct AnswerverifiedShow Answer

A frameshift mutation could result from

Correct AnswerverifiedShow Answer

RNA polymerase moves in which direction along the DNA?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified