Cell Biology 112 Exam 3 PCC | 2025/2026
Edition Pasadena City College | Advanced
Cellular Processes Assessment
Overview
This 2025/2026 validated resource contains a comprehensive Cell Biology
112 Exam 3 practice examination from Pasadena City College with expertly
crafted questions and verified answers, directly aligned with current PCC
curriculum standards. Essential for biology students preparing for advanced
cellular processes assessment and demonstrating competency in genetic
information flow, cell signaling, and regulatory mechanisms.
Key Features
✓ 65-Question Comprehensive Exam matching PCC assessment format
✓ Genetic Information Processing with molecular applications
✓ Cell Signaling Pathways with regulatory mechanisms
✓ Updated 2025/2026 PCC cell biology curriculum standards
✓ Experimental Design & Data Interpretation with research applications
✓ Detailed Rationales for every answer with molecular mechanism
explanations
Content Domains
Question Weigh
Content Area Key Topics
s t
DNA
Replication & 13 ORC, primase, DNA polymerases, 20%
Repair Okazaki fragments, mismatch
, Question Weigh
Content Area Key Topics
s t
repair, telomerase, FANC
pathway
RNA polymerases, promoters,
Transcriptio
splicing, capping,
n & RNA 10 15%
polyadenylation, non-coding
Processing
RNAs
Translation Ribosomes, tRNA,
& Protein 10 initiation/elongation/terminatio 15%
Synthesis n, antibiotics, protein targeting
Receptor types, second
Cell Signaling
messengers, kinase cascades,
& Signal 12 18%
GPCRs, RTKs,
Transduction
endocrine/paracrine/autocrine
Gene Operons, transcription factors,
Regulation & 10 epigenetics, chromatin 15%
Expression remodeling, enhancers/silencers
Research PCR, gel electrophoresis, CRISPR,
Methods & 10 microscopy, flow cytometry, data 15%
Analysis interpretation
Answer Format
Verified correct answers are displayed in bold with:
• Molecular pathway explanations
, • Regulatory mechanism rationales
• Experimental design justifications
• Data interpretation methodologies
Critical Updates 2025/2026
• NEW - CRISPR technology applications and mechanisms
• UPDATED - Epigenetic modification mechanisms (DNA methylation,
histone modifications)
• REVISED - Non-coding RNA functions (miRNA, lncRNA, siRNA)
• MODIFIED - Signal transduction pathway analysis with current
research findings
1. The Origin Recognition Complex (ORC) binds to replication origins
during which phase of the cell cycle?
• A. G₁ phase
• B. S phase
• C. G₂ phase
• D. M phase
Correct Answer: A. G₁ phase
Rationale: The Origin Recognition Complex (ORC) binds to replication origins
during G₁ phase to "license" them for a single firing per cell cycle. This ensures
that each origin is activated only once during S phase. The ORC remains bound
throughout the cell cycle but is only competent to recruit additional
replication factors (Cdc6, Cdt1, and MCM helicase) during G₁. Once replication
initiates in S phase, the origins cannot fire again until the next cell cycle.
Why Wrong: B is incorrect (S phase is when replication occurs, not when ORC
binds); C is incorrect (G₂ is after replication); D is incorrect (M phase is
chromosome segregation).
, Reference: Alberts, B., et al. Molecular Biology of the Cell (7th ed.). Garland
Science, 2024.
2. The catalytic subunit of human DNA primase is:
• A. PRIM1
• B. PRIM2
• C. POLA1
• D. RNASEH2A
Correct Answer: B. PRIM2
Rationale: PRIM2 (p58 subunit) is the catalytic subunit of DNA primase,
which synthesizes the RNA primer needed for DNA polymerase to initiate
replication. Primase is a specialized RNA polymerase that synthesizes short
RNA primers complementary to the DNA template. These primers provide the
free 3'-OH group required by DNA polymerases for nucleotide addition.
Why Wrong: A is incorrect (PRIM1 is the regulatory subunit); C is incorrect
(POLA1 is DNA polymerase α, which extends RNA primers with DNA); D is
incorrect (RNASEH2A removes RNA primers).
Reference: Lodish, H., et al. Molecular Cell Biology (10th ed.). W.H. Freeman,
2025.
3. Which DNA polymerase fills Okazaki fragments in human cells?
• A. Pol α
• B. Pol δ
• C. Pol ε
• D. Pol γ
Correct Answer: B. Pol δ
Rationale: DNA polymerase δ (Pol δ) possesses 3'→5' exonuclease activity for
proofreading and high processivity, making it the primary polymerase for
Edition Pasadena City College | Advanced
Cellular Processes Assessment
Overview
This 2025/2026 validated resource contains a comprehensive Cell Biology
112 Exam 3 practice examination from Pasadena City College with expertly
crafted questions and verified answers, directly aligned with current PCC
curriculum standards. Essential for biology students preparing for advanced
cellular processes assessment and demonstrating competency in genetic
information flow, cell signaling, and regulatory mechanisms.
Key Features
✓ 65-Question Comprehensive Exam matching PCC assessment format
✓ Genetic Information Processing with molecular applications
✓ Cell Signaling Pathways with regulatory mechanisms
✓ Updated 2025/2026 PCC cell biology curriculum standards
✓ Experimental Design & Data Interpretation with research applications
✓ Detailed Rationales for every answer with molecular mechanism
explanations
Content Domains
Question Weigh
Content Area Key Topics
s t
DNA
Replication & 13 ORC, primase, DNA polymerases, 20%
Repair Okazaki fragments, mismatch
, Question Weigh
Content Area Key Topics
s t
repair, telomerase, FANC
pathway
RNA polymerases, promoters,
Transcriptio
splicing, capping,
n & RNA 10 15%
polyadenylation, non-coding
Processing
RNAs
Translation Ribosomes, tRNA,
& Protein 10 initiation/elongation/terminatio 15%
Synthesis n, antibiotics, protein targeting
Receptor types, second
Cell Signaling
messengers, kinase cascades,
& Signal 12 18%
GPCRs, RTKs,
Transduction
endocrine/paracrine/autocrine
Gene Operons, transcription factors,
Regulation & 10 epigenetics, chromatin 15%
Expression remodeling, enhancers/silencers
Research PCR, gel electrophoresis, CRISPR,
Methods & 10 microscopy, flow cytometry, data 15%
Analysis interpretation
Answer Format
Verified correct answers are displayed in bold with:
• Molecular pathway explanations
, • Regulatory mechanism rationales
• Experimental design justifications
• Data interpretation methodologies
Critical Updates 2025/2026
• NEW - CRISPR technology applications and mechanisms
• UPDATED - Epigenetic modification mechanisms (DNA methylation,
histone modifications)
• REVISED - Non-coding RNA functions (miRNA, lncRNA, siRNA)
• MODIFIED - Signal transduction pathway analysis with current
research findings
1. The Origin Recognition Complex (ORC) binds to replication origins
during which phase of the cell cycle?
• A. G₁ phase
• B. S phase
• C. G₂ phase
• D. M phase
Correct Answer: A. G₁ phase
Rationale: The Origin Recognition Complex (ORC) binds to replication origins
during G₁ phase to "license" them for a single firing per cell cycle. This ensures
that each origin is activated only once during S phase. The ORC remains bound
throughout the cell cycle but is only competent to recruit additional
replication factors (Cdc6, Cdt1, and MCM helicase) during G₁. Once replication
initiates in S phase, the origins cannot fire again until the next cell cycle.
Why Wrong: B is incorrect (S phase is when replication occurs, not when ORC
binds); C is incorrect (G₂ is after replication); D is incorrect (M phase is
chromosome segregation).
, Reference: Alberts, B., et al. Molecular Biology of the Cell (7th ed.). Garland
Science, 2024.
2. The catalytic subunit of human DNA primase is:
• A. PRIM1
• B. PRIM2
• C. POLA1
• D. RNASEH2A
Correct Answer: B. PRIM2
Rationale: PRIM2 (p58 subunit) is the catalytic subunit of DNA primase,
which synthesizes the RNA primer needed for DNA polymerase to initiate
replication. Primase is a specialized RNA polymerase that synthesizes short
RNA primers complementary to the DNA template. These primers provide the
free 3'-OH group required by DNA polymerases for nucleotide addition.
Why Wrong: A is incorrect (PRIM1 is the regulatory subunit); C is incorrect
(POLA1 is DNA polymerase α, which extends RNA primers with DNA); D is
incorrect (RNASEH2A removes RNA primers).
Reference: Lodish, H., et al. Molecular Cell Biology (10th ed.). W.H. Freeman,
2025.
3. Which DNA polymerase fills Okazaki fragments in human cells?
• A. Pol α
• B. Pol δ
• C. Pol ε
• D. Pol γ
Correct Answer: B. Pol δ
Rationale: DNA polymerase δ (Pol δ) possesses 3'→5' exonuclease activity for
proofreading and high processivity, making it the primary polymerase for
