Molecular Biology (Study Guide
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**Question 1**
- **Description:** Initiation of DNA replication in prokaryotes.
- **Keywords:** OriC, DnaA, replication fork, initiator protein.
- **Question:** In *E. coli*, which protein binds to the DnaA box sequences within the origin of
replication (oriC) to initiate strand separation and recruit the helicase loader?
- A) DnaB
- B) DnaC
- C) DnaA ✅✅✅
- D) SSB
**Question 2**
- **Description:** Mechanism of DNA polymerase proofreading.
- **Keywords:** 3'→5' exonuclease, mismatch repair, fidelity.
,- **Question:** The high fidelity of DNA replication is primarily due to which intrinsic activity of
DNA polymerase III?
- A) 5'→3' polymerase activity
- B) 3'→5' exonuclease activity ✅✅✅
- C) 5'→3' exonuclease activity
- D) Endonuclease activity
**Question 3**
- **Description:** Function of telomeres and telomerase.
- **Keywords:** End-replication problem, lagging strand, senescence.
- **Question:** Which statement correctly describes the role of telomerase in eukaryotic DNA
replication?
- A) It synthesizes RNA primers on the lagging strand.
- B) It extends the 3' end of the parental template strand using its own RNA template. ✅✅✅
- C) It removes supercoils ahead of the replication fork.
- D) It seals nicks between Okazaki fragments.
**Question 4**
- **Description:** Directionality of DNA synthesis.
- **Keywords:** 5'→3', antiparallel, leading strand.
- **Question:** All known DNA polymerases synthesize new DNA strands in which direction?
- A) 3'→5' only
- B) 5'→3' only ✅✅✅
- C) Both 5'→3' and 3'→5'
- D) Random direction depending on the template
,**Question 5**
- **Description:** Enzyme responsible for relieving torsional stress.
- **Keywords:** Topoisomerase, supercoiling, gyrase.
- **Question:** During DNA replication, which enzyme prevents supercoiling ahead of the
replication fork by cutting and resealing DNA strands?
- A) Helicase
- B) DNA ligase
- C) Topoisomerase ✅✅✅
- D) Primase
**Question 6**
- **Description:** RNA primer removal in prokaryotes vs. eukaryotes.
- **Keywords:** Okazaki fragments, RNase H, FEN1, DNA polymerase I.
- **Question:** In *E. coli*, removal of RNA primers from Okazaki fragments is primarily
performed by:
- A) DNA polymerase III
- B) DNA polymerase I ✅✅✅
- C) RNase H alone
- D) Primase
**Question 7**
- **Description:** Eukaryotic DNA polymerase for lagging strand synthesis.
- **Keywords:** Pol δ, PCNA, processivity.
- **Question:** Which eukaryotic DNA polymerase is primarily responsible for extending
Okazaki fragments on the lagging strand?
- A) DNA polymerase α
- B) DNA polymerase β
, - C) DNA polymerase δ ✅✅✅
- D) DNA polymerase γ
**Question 8**
- **Description:** Initiation of transcription in bacteria.
- **Keywords:** Sigma factor, core RNA polymerase, holoenzyme, promoter.
- **Question:** The specificity of bacterial RNA polymerase for promoter regions is determined
by:
- A) Rho factor
- B) Sigma (σ) factor ✅✅✅
- C) TATA-binding protein (TBP)
- D) TFIIH
**Question 9**
- **Description:** Function of the 5' cap on eukaryotic mRNA.
- **Keywords:** 7-methylguanylate, stability, translation initiation, export.
- **Question:** Which of the following is NOT a function of the 5' 7-methylguanosine cap of
eukaryotic mRNA?
- A) Protection from 5'→3' exonucleases
- B) Facilitating nuclear export
- C) Providing a binding site for the small ribosomal subunit
- D) Serving as a template for polyadenylation ✅✅✅
**Question 10**
- **Description:** Polyadenylation signal sequence.
- **Keywords:** AAUAAA, cleavage and polyadenylation specificity factor (CPSF).
2026/2027 - Complete
Questions with Verified Correct
Answers || 100% Guaranteed
Pass - Newest Version)
---
**Question 1**
- **Description:** Initiation of DNA replication in prokaryotes.
- **Keywords:** OriC, DnaA, replication fork, initiator protein.
- **Question:** In *E. coli*, which protein binds to the DnaA box sequences within the origin of
replication (oriC) to initiate strand separation and recruit the helicase loader?
- A) DnaB
- B) DnaC
- C) DnaA ✅✅✅
- D) SSB
**Question 2**
- **Description:** Mechanism of DNA polymerase proofreading.
- **Keywords:** 3'→5' exonuclease, mismatch repair, fidelity.
,- **Question:** The high fidelity of DNA replication is primarily due to which intrinsic activity of
DNA polymerase III?
- A) 5'→3' polymerase activity
- B) 3'→5' exonuclease activity ✅✅✅
- C) 5'→3' exonuclease activity
- D) Endonuclease activity
**Question 3**
- **Description:** Function of telomeres and telomerase.
- **Keywords:** End-replication problem, lagging strand, senescence.
- **Question:** Which statement correctly describes the role of telomerase in eukaryotic DNA
replication?
- A) It synthesizes RNA primers on the lagging strand.
- B) It extends the 3' end of the parental template strand using its own RNA template. ✅✅✅
- C) It removes supercoils ahead of the replication fork.
- D) It seals nicks between Okazaki fragments.
**Question 4**
- **Description:** Directionality of DNA synthesis.
- **Keywords:** 5'→3', antiparallel, leading strand.
- **Question:** All known DNA polymerases synthesize new DNA strands in which direction?
- A) 3'→5' only
- B) 5'→3' only ✅✅✅
- C) Both 5'→3' and 3'→5'
- D) Random direction depending on the template
,**Question 5**
- **Description:** Enzyme responsible for relieving torsional stress.
- **Keywords:** Topoisomerase, supercoiling, gyrase.
- **Question:** During DNA replication, which enzyme prevents supercoiling ahead of the
replication fork by cutting and resealing DNA strands?
- A) Helicase
- B) DNA ligase
- C) Topoisomerase ✅✅✅
- D) Primase
**Question 6**
- **Description:** RNA primer removal in prokaryotes vs. eukaryotes.
- **Keywords:** Okazaki fragments, RNase H, FEN1, DNA polymerase I.
- **Question:** In *E. coli*, removal of RNA primers from Okazaki fragments is primarily
performed by:
- A) DNA polymerase III
- B) DNA polymerase I ✅✅✅
- C) RNase H alone
- D) Primase
**Question 7**
- **Description:** Eukaryotic DNA polymerase for lagging strand synthesis.
- **Keywords:** Pol δ, PCNA, processivity.
- **Question:** Which eukaryotic DNA polymerase is primarily responsible for extending
Okazaki fragments on the lagging strand?
- A) DNA polymerase α
- B) DNA polymerase β
, - C) DNA polymerase δ ✅✅✅
- D) DNA polymerase γ
**Question 8**
- **Description:** Initiation of transcription in bacteria.
- **Keywords:** Sigma factor, core RNA polymerase, holoenzyme, promoter.
- **Question:** The specificity of bacterial RNA polymerase for promoter regions is determined
by:
- A) Rho factor
- B) Sigma (σ) factor ✅✅✅
- C) TATA-binding protein (TBP)
- D) TFIIH
**Question 9**
- **Description:** Function of the 5' cap on eukaryotic mRNA.
- **Keywords:** 7-methylguanylate, stability, translation initiation, export.
- **Question:** Which of the following is NOT a function of the 5' 7-methylguanosine cap of
eukaryotic mRNA?
- A) Protection from 5'→3' exonucleases
- B) Facilitating nuclear export
- C) Providing a binding site for the small ribosomal subunit
- D) Serving as a template for polyadenylation ✅✅✅
**Question 10**
- **Description:** Polyadenylation signal sequence.
- **Keywords:** AAUAAA, cleavage and polyadenylation specificity factor (CPSF).
