BIOC 385 Metabolic Biochemistry Exam 4 Review
Test Bank B - 300 Latest Real Exam Questions with
Correct Answers and Well-elaborated Rationales /
BIOC 385 Exam 4 Latest 2026-2027 University of
Arizona/ Biochem 385 Exam 4
1: Which base location in the figure below (A, B, C, D) explains the wobble
hypothesis?
A. A
B. B
1
,C. C
D. D
-ANSWER- D
Rationale: D explains the wobble hypothesis.
2: In the figure show below of an E. coli replication fork, which protein is
responsible for relieving torsional stress?
A. Gyrase
-ANSWER- A
Rationale: Helicase is responsible for unwinding the DNA duplex for replication.
This action leads to torsional strain upstream of the replication fork, which would
inhibit forward movement of the fork. Gyrase, which is a type II topoisomerase,
relieves this strain.
3: The roles of U1, U2, U4, U5, and U6 in the spliceosome complex are
to________________.
A. Carry the products from the nucleus to the cytoplasm.
B. Bind mRNA and facilitate the splicing reaction.
C. Bind proteins and hold the complex together.
D. Bind the small nuclear RNA.
-ANSWER- B
2
,Rationale: The roles of U1, U2, U4, U5, and U6 in the spliceosome complex are to
bind mRNA and facilitate the splicing reaction.
4: Which of the following statements is correct regarding spliceosome-mediated
trans splicing?
A. The spliceosome mechanism involves two transesterification reactions.
B. The snRNPs involved in splicing are not recycled.
C. The spliceosome mechanism closely resembles the mechanism of group I
introns.
D. The spliceosome is composed only of proteins.
-ANSWER- A
Rationale: The spliceosome mechanism involves two transesterification reactions.
5: Which three experiments were used to decipher the 64 codons of the Genetic
Code?
A. RNA heteropolymers, repeating trinucleotides, radioactive mRNA
B. RNA homopolymers, repeating amino acids, radioactive AA-tRNA
C. DNA codons, antisense trinucleotides, radioactive rRNA
D. RNA homopolymers, repeating trinucleotides, radioactive AA-tRNA
-ANSWER- D
Rationale: The three experiments used to decipher the 64 codons were RNA
homopolymers, repeating trinucleotides, and radioactive AA-tRNA.
6: The initiation of transcription in eukaryotes_________________.
A. Requires many more transcription factors than prokaryotic transcription.
B. Occurs in the same manner as prokaryotic transcription.
C. Requires the complete unfolding of the gene into single-stranded DNA.
D. Uses RNA polymerase as well as helicase and primase.
-ANSWER- A
Rationale: The initiation of transcription in eukaryotes requires many more
transcription factors than prokaryotic transcription.
7: What explains the observation that a single eukaryotic protein coding gene can
give rise to multiple different proteins, i.e., why are there only ~25,000 human
genes in the genome, but ~150,000 different proteins in the human "proteome?"
Choose the TWO best answers.
A. Some genes are transcribed from both strands of the DNA and this generates
isozymes of the same protein.
B. Serine phosphorylation of a polypeptide changes its amino acid sequence, and
3
, thereby generates multiple proteins from the same gene.
C. Polypeptide subunits of the same protein complexes are often differentially
cleaved by protease enzymes, resulting in loss of some subunits and duplication of
others.
D. Genes can contain more than one polyadenylation site, which alters the 3' of the
mRNA transcript and the inclusion/exclusion of exons.
E. mRNA transcripts from the same gene can be differentially spliced to
include/exclude exons.
-ANSWER- D, E
Rationale: Genes can contain more than one polyadenylation site, which alters the
3' of the mRNA transcript and the inclusion/exclusion of exons. mRNA transcripts
from the same gene can be differentially spliced to include/exclude exons.
8: If tRNAs are charged with radioactively-labeled amino acids in an in vitro
system, then over time the radioactivity will be located in newly synthesized
______________.
A. Codons
B. mRNA
C. Protein
D. Aminoacyl tRNA synthetase
-ANSWER- C
Rationale: If tRNAs are charged with radioactively-labeled amino acids in an in
vitro system, then over time the radioactivity will be located in newly synthesized
protein.
9: Francis Crick hypothesized that the Genetic Code must require 3 nucleotides in
the mRNA to specify each amino acid based on a simple calculation. What was the
logic behind this calculation? Choose the ONE best answer.
A. Based on the number of known amino acids and the number of known
nucleotide bases.
B. Based on the number of known amino acids and the number of known tRNA
molecules.
C. 4 x 4 = 16, whereas 4 x 4 x 3 = 48, and since there are 20 amino acids, it must
require 3 codons (48 > 16).
D. Based on the number of known tRNA molecules and the number of known
nucleotide bases.
E. On the fact that thymine is present in DNA but uracil is present in RNA, each of
which base pair with adenine.
4
Test Bank B - 300 Latest Real Exam Questions with
Correct Answers and Well-elaborated Rationales /
BIOC 385 Exam 4 Latest 2026-2027 University of
Arizona/ Biochem 385 Exam 4
1: Which base location in the figure below (A, B, C, D) explains the wobble
hypothesis?
A. A
B. B
1
,C. C
D. D
-ANSWER- D
Rationale: D explains the wobble hypothesis.
2: In the figure show below of an E. coli replication fork, which protein is
responsible for relieving torsional stress?
A. Gyrase
-ANSWER- A
Rationale: Helicase is responsible for unwinding the DNA duplex for replication.
This action leads to torsional strain upstream of the replication fork, which would
inhibit forward movement of the fork. Gyrase, which is a type II topoisomerase,
relieves this strain.
3: The roles of U1, U2, U4, U5, and U6 in the spliceosome complex are
to________________.
A. Carry the products from the nucleus to the cytoplasm.
B. Bind mRNA and facilitate the splicing reaction.
C. Bind proteins and hold the complex together.
D. Bind the small nuclear RNA.
-ANSWER- B
2
,Rationale: The roles of U1, U2, U4, U5, and U6 in the spliceosome complex are to
bind mRNA and facilitate the splicing reaction.
4: Which of the following statements is correct regarding spliceosome-mediated
trans splicing?
A. The spliceosome mechanism involves two transesterification reactions.
B. The snRNPs involved in splicing are not recycled.
C. The spliceosome mechanism closely resembles the mechanism of group I
introns.
D. The spliceosome is composed only of proteins.
-ANSWER- A
Rationale: The spliceosome mechanism involves two transesterification reactions.
5: Which three experiments were used to decipher the 64 codons of the Genetic
Code?
A. RNA heteropolymers, repeating trinucleotides, radioactive mRNA
B. RNA homopolymers, repeating amino acids, radioactive AA-tRNA
C. DNA codons, antisense trinucleotides, radioactive rRNA
D. RNA homopolymers, repeating trinucleotides, radioactive AA-tRNA
-ANSWER- D
Rationale: The three experiments used to decipher the 64 codons were RNA
homopolymers, repeating trinucleotides, and radioactive AA-tRNA.
6: The initiation of transcription in eukaryotes_________________.
A. Requires many more transcription factors than prokaryotic transcription.
B. Occurs in the same manner as prokaryotic transcription.
C. Requires the complete unfolding of the gene into single-stranded DNA.
D. Uses RNA polymerase as well as helicase and primase.
-ANSWER- A
Rationale: The initiation of transcription in eukaryotes requires many more
transcription factors than prokaryotic transcription.
7: What explains the observation that a single eukaryotic protein coding gene can
give rise to multiple different proteins, i.e., why are there only ~25,000 human
genes in the genome, but ~150,000 different proteins in the human "proteome?"
Choose the TWO best answers.
A. Some genes are transcribed from both strands of the DNA and this generates
isozymes of the same protein.
B. Serine phosphorylation of a polypeptide changes its amino acid sequence, and
3
, thereby generates multiple proteins from the same gene.
C. Polypeptide subunits of the same protein complexes are often differentially
cleaved by protease enzymes, resulting in loss of some subunits and duplication of
others.
D. Genes can contain more than one polyadenylation site, which alters the 3' of the
mRNA transcript and the inclusion/exclusion of exons.
E. mRNA transcripts from the same gene can be differentially spliced to
include/exclude exons.
-ANSWER- D, E
Rationale: Genes can contain more than one polyadenylation site, which alters the
3' of the mRNA transcript and the inclusion/exclusion of exons. mRNA transcripts
from the same gene can be differentially spliced to include/exclude exons.
8: If tRNAs are charged with radioactively-labeled amino acids in an in vitro
system, then over time the radioactivity will be located in newly synthesized
______________.
A. Codons
B. mRNA
C. Protein
D. Aminoacyl tRNA synthetase
-ANSWER- C
Rationale: If tRNAs are charged with radioactively-labeled amino acids in an in
vitro system, then over time the radioactivity will be located in newly synthesized
protein.
9: Francis Crick hypothesized that the Genetic Code must require 3 nucleotides in
the mRNA to specify each amino acid based on a simple calculation. What was the
logic behind this calculation? Choose the ONE best answer.
A. Based on the number of known amino acids and the number of known
nucleotide bases.
B. Based on the number of known amino acids and the number of known tRNA
molecules.
C. 4 x 4 = 16, whereas 4 x 4 x 3 = 48, and since there are 20 amino acids, it must
require 3 codons (48 > 16).
D. Based on the number of known tRNA molecules and the number of known
nucleotide bases.
E. On the fact that thymine is present in DNA but uracil is present in RNA, each of
which base pair with adenine.
4
