BIOL 304: MOLECULAR CELL BIOLOGY &
GENETICS QUESTIONS AND ANSWERS
WITH RATIONALES/ GRADED A+/2026
UPDATE /100% PASS
Section I: Multiple Choice (60 Questions, 1 point each)
Topic: Transcription & RNA Processing
1. Which of the following is the primary function of the Mediator complex in eukaryotic
transcription?
a) Unwinding DNA at the transcription start site
b) Capping the nascent pre-mRNA
c) Transmitting signals from activators/repressors to RNA Polymerase II
d) Polyadenylating the 3’ end of the transcript
Answer: c) Transmitting signals from activators/repressors to RNA Polymerase II
Rationale: Mediator is a large protein complex that acts as a bridge between transcription
factors bound to enhancers and the RNA Polymerase II holoenzyme, facilitating the assembly of
the pre-initiation complex.
2. A scientist discovers a mutation that prevents the addition of the 5’ cap to pre-mRNA. What is
the most direct consequence of this mutation?
a) The transcript will not be spliced.
b) The transcript will be rapidly degraded by exonucleases.
c) Poly-A polymerase will not be recruited.
d) The ribosome will translate the mRNA into a truncated protein.
Answer: b) The transcript will be rapidly degraded by exonucleases.
Rationale: The 5’ cap protects the nascent mRNA from degradation by 5’→3’ exonucleases.
Without it, the RNA is unstable and quickly degraded.
3. Alternative splicing allows for:
a) The production of multiple proteins from a single gene.
b) The editing of RNA bases to alter the protein sequence.
, c) The addition of a poly-A tail to different splice variants.
d) The transport of mRNA out of the nucleus only after complete splicing.
Answer: a) The production of multiple proteins from a single gene.
Rationale: By including or excluding different exons, a single primary transcript can be processed
into multiple mature mRNA variants, leading to protein diversity.
4. Small nuclear ribonucleoproteins (snRNPs) are critical components of the spliceosome. Their
primary role is to:
a) Catalyze the peptide bond formation.
b) Recognize the 5’ splice site and branch point via RNA-RNA interactions.
c) Unwind the DNA double helix.
d) Add the poly-A tail.
Answer: b) Recognize the 5’ splice site and branch point via RNA-RNA interactions.
*Rationale: snRNPs (U1, U2, etc.) contain snRNA molecules that base-pair with the consensus
sequences at the 5’ splice site and the branch point adenine, positioning them for the
transesterification reactions of splicing.*
5. Which RNA polymerase is responsible for transcribing most ribosomal RNA (rRNA) genes in
eukaryotes?
a) RNA Polymerase I
b) RNA Polymerase II
c) RNA Polymerase III
d) RNA Polymerase IV
Answer: a) RNA Polymerase I
Rationale: RNA Pol I transcribes rRNA genes (except 5S rRNA). RNA Pol II transcribes mRNA and
some snRNAs. RNA Pol III transcribes tRNA, 5S rRNA, and other small RNAs.
Topic: Translation & Protein Folding
6. The Shine-Dalgarno sequence is a ribosomal binding site found in:
a) Eukaryotic mRNA
b) Prokaryotic mRNA
c) Eukaryotic rRNA
d) tRNA anticodons
Answer: b) Prokaryotic mRNA
*Rationale: In prokaryotes, the Shine-Dalgarno sequence (AGGAGGU) upstream of the start
codon base-pairs with the 16S rRNA of the 30S ribosomal subunit to position the ribosome
correctly for initiation. Eukaryotes use a 5’ cap scanning mechanism instead.*
7. During translation elongation, the peptidyl transferase activity is a function of:
a) The EF-Tu (eEF1A) elongation factor
b) The large ribosomal subunit’s rRNA (23S in bacteria, 28S in eukaryotes)
, c) The small ribosomal subunit’s proteins
d) The tRNA synthetase
Answer: b) The large ribosomal subunit’s rRNA (23S in bacteria, 28S in eukaryotes)
Rationale: The ribosome is a ribozyme. Peptidyl transferase, which forms the peptide bond, is
catalyzed by the rRNA component of the large subunit, not by ribosomal proteins.
8. Chaperone proteins, such as Hsp70, function to:
a) Degrade misfolded proteins via the proteasome.
b) Catalyze the formation of disulfide bonds.
c) Assist in proper protein folding and prevent aggregation.
d) Cleave signal sequences from nascent polypeptides.
Answer: c) Assist in proper protein folding and prevent aggregation.
Rationale: Chaperones bind to exposed hydrophobic patches on nascent or unfolded proteins,
providing a protected environment for correct folding and preventing inappropriate interactions
that lead to aggregation.
9. A drug that inhibits EF-G (eEF2 in eukaryotes) would directly block:
a) Initiation of translation
b) Aminoacyl-tRNA charging
c) Translocation of the ribosome along the mRNA
d) Peptide bond formation
Answer: c) Translocation of the ribosome along the mRNA
*Rationale: EF-G (eEF2) is the elongation factor that, upon GTP hydrolysis, facilitates the
movement (translocation) of the ribosome by one codon, shifting the tRNAs from the A and P
sites to the P and E sites.*
10. The unfolded protein response (UPR) is activated in response to:
a) DNA damage
b) Accumulation of misfolded proteins in the endoplasmic reticulum (ER)
c) High levels of ATP in the mitochondria
d) Low levels of glucose in the cytoplasm
Answer: b) Accumulation of misfolded proteins in the endoplasmic reticulum (ER)
Rationale: The UPR is a cellular stress response triggered by an overload of misfolded or unfolded
proteins in the ER lumen. It aims to restore ER homeostasis by reducing translation and
increasing the production of ER chaperones.
Topic: Cell Signaling
11. Which of the following best describes the role of a GTPase-activating protein (GAP)?
a) Promotes the exchange of GDP for GTP on a small GTPase
b) Increases the intrinsic GTP hydrolysis rate of a small GTPase
c) Prevents the interaction of a GTPase with its effector
GENETICS QUESTIONS AND ANSWERS
WITH RATIONALES/ GRADED A+/2026
UPDATE /100% PASS
Section I: Multiple Choice (60 Questions, 1 point each)
Topic: Transcription & RNA Processing
1. Which of the following is the primary function of the Mediator complex in eukaryotic
transcription?
a) Unwinding DNA at the transcription start site
b) Capping the nascent pre-mRNA
c) Transmitting signals from activators/repressors to RNA Polymerase II
d) Polyadenylating the 3’ end of the transcript
Answer: c) Transmitting signals from activators/repressors to RNA Polymerase II
Rationale: Mediator is a large protein complex that acts as a bridge between transcription
factors bound to enhancers and the RNA Polymerase II holoenzyme, facilitating the assembly of
the pre-initiation complex.
2. A scientist discovers a mutation that prevents the addition of the 5’ cap to pre-mRNA. What is
the most direct consequence of this mutation?
a) The transcript will not be spliced.
b) The transcript will be rapidly degraded by exonucleases.
c) Poly-A polymerase will not be recruited.
d) The ribosome will translate the mRNA into a truncated protein.
Answer: b) The transcript will be rapidly degraded by exonucleases.
Rationale: The 5’ cap protects the nascent mRNA from degradation by 5’→3’ exonucleases.
Without it, the RNA is unstable and quickly degraded.
3. Alternative splicing allows for:
a) The production of multiple proteins from a single gene.
b) The editing of RNA bases to alter the protein sequence.
, c) The addition of a poly-A tail to different splice variants.
d) The transport of mRNA out of the nucleus only after complete splicing.
Answer: a) The production of multiple proteins from a single gene.
Rationale: By including or excluding different exons, a single primary transcript can be processed
into multiple mature mRNA variants, leading to protein diversity.
4. Small nuclear ribonucleoproteins (snRNPs) are critical components of the spliceosome. Their
primary role is to:
a) Catalyze the peptide bond formation.
b) Recognize the 5’ splice site and branch point via RNA-RNA interactions.
c) Unwind the DNA double helix.
d) Add the poly-A tail.
Answer: b) Recognize the 5’ splice site and branch point via RNA-RNA interactions.
*Rationale: snRNPs (U1, U2, etc.) contain snRNA molecules that base-pair with the consensus
sequences at the 5’ splice site and the branch point adenine, positioning them for the
transesterification reactions of splicing.*
5. Which RNA polymerase is responsible for transcribing most ribosomal RNA (rRNA) genes in
eukaryotes?
a) RNA Polymerase I
b) RNA Polymerase II
c) RNA Polymerase III
d) RNA Polymerase IV
Answer: a) RNA Polymerase I
Rationale: RNA Pol I transcribes rRNA genes (except 5S rRNA). RNA Pol II transcribes mRNA and
some snRNAs. RNA Pol III transcribes tRNA, 5S rRNA, and other small RNAs.
Topic: Translation & Protein Folding
6. The Shine-Dalgarno sequence is a ribosomal binding site found in:
a) Eukaryotic mRNA
b) Prokaryotic mRNA
c) Eukaryotic rRNA
d) tRNA anticodons
Answer: b) Prokaryotic mRNA
*Rationale: In prokaryotes, the Shine-Dalgarno sequence (AGGAGGU) upstream of the start
codon base-pairs with the 16S rRNA of the 30S ribosomal subunit to position the ribosome
correctly for initiation. Eukaryotes use a 5’ cap scanning mechanism instead.*
7. During translation elongation, the peptidyl transferase activity is a function of:
a) The EF-Tu (eEF1A) elongation factor
b) The large ribosomal subunit’s rRNA (23S in bacteria, 28S in eukaryotes)
, c) The small ribosomal subunit’s proteins
d) The tRNA synthetase
Answer: b) The large ribosomal subunit’s rRNA (23S in bacteria, 28S in eukaryotes)
Rationale: The ribosome is a ribozyme. Peptidyl transferase, which forms the peptide bond, is
catalyzed by the rRNA component of the large subunit, not by ribosomal proteins.
8. Chaperone proteins, such as Hsp70, function to:
a) Degrade misfolded proteins via the proteasome.
b) Catalyze the formation of disulfide bonds.
c) Assist in proper protein folding and prevent aggregation.
d) Cleave signal sequences from nascent polypeptides.
Answer: c) Assist in proper protein folding and prevent aggregation.
Rationale: Chaperones bind to exposed hydrophobic patches on nascent or unfolded proteins,
providing a protected environment for correct folding and preventing inappropriate interactions
that lead to aggregation.
9. A drug that inhibits EF-G (eEF2 in eukaryotes) would directly block:
a) Initiation of translation
b) Aminoacyl-tRNA charging
c) Translocation of the ribosome along the mRNA
d) Peptide bond formation
Answer: c) Translocation of the ribosome along the mRNA
*Rationale: EF-G (eEF2) is the elongation factor that, upon GTP hydrolysis, facilitates the
movement (translocation) of the ribosome by one codon, shifting the tRNAs from the A and P
sites to the P and E sites.*
10. The unfolded protein response (UPR) is activated in response to:
a) DNA damage
b) Accumulation of misfolded proteins in the endoplasmic reticulum (ER)
c) High levels of ATP in the mitochondria
d) Low levels of glucose in the cytoplasm
Answer: b) Accumulation of misfolded proteins in the endoplasmic reticulum (ER)
Rationale: The UPR is a cellular stress response triggered by an overload of misfolded or unfolded
proteins in the ER lumen. It aims to restore ER homeostasis by reducing translation and
increasing the production of ER chaperones.
Topic: Cell Signaling
11. Which of the following best describes the role of a GTPase-activating protein (GAP)?
a) Promotes the exchange of GDP for GTP on a small GTPase
b) Increases the intrinsic GTP hydrolysis rate of a small GTPase
c) Prevents the interaction of a GTPase with its effector
