DNA replication is the fundamental process by which a cell duplicates its genome, a feat of remarkable speed and precision. While the basic principles are conserved, prokaryotes and eukaryotes have evolved distinct strategies and enzymatic machinery to accomplish this task. For PharmD students, understanding these differences is key to grasping the mechanisms of antimicrobial and anticancer drugs that target this vital process. This quiz will test your knowledge of the similarities and differences in how these two domains of life copy their DNA.
1. DNA replication is described as “semiconservative,” which means that:
- One of the parent strands is completely degraded.
- The two new DNA molecules are a random mix of old and new DNA.
- Each new DNA double helix consists of one old parent strand and one newly synthesized strand.
- The entire parent double helix is conserved, and a completely new double helix is made.
Answer: Each new DNA double helix consists of one old parent strand and one newly synthesized strand.
2. DNA synthesis always proceeds in which direction?
- 3′ to 5′
- 5′ to 3′
- From the centromere to the telomere.
- In both directions simultaneously on a single strand.
Answer: 5′ to 3′
3. A key structural difference that leads to major differences in the replication process is that prokaryotic chromosomes are typically ________, while eukaryotic chromosomes are ________.
- Linear; circular
- Circular; linear
- Single-stranded; double-stranded
- Made of RNA; made of DNA
Answer: Circular; linear
4. How many origins of replication are typically found in a bacterial (prokaryotic) chromosome?
- One
- Two
- Dozens
- Hundreds to thousands
Answer: One
5. Eukaryotic chromosomes require multiple origins of replication because:
- They are much larger and replication from a single origin would be too slow.
- They replicate in a unidirectional manner.
- Their DNA polymerase is much slower than the prokaryotic version.
- They lack the enzyme helicase.
Answer: They are much larger and replication from a single origin would be too slow.
6. The enzyme responsible for unwinding the DNA double helix at the replication fork is:
- DNA Polymerase
- DNA Ligase
- Helicase
- Primase
Answer: Helicase
7. DNA polymerase requires a pre-existing 3′-OH group to begin synthesis. This is provided by a short RNA sequence synthesized by which enzyme?
- Topoisomerase
- Primase
- Ligase
- Helicase
Answer: Primase
8. The “leading strand” is synthesized ________, while the “lagging strand” is synthesized ________.
- Discontinuously; continuously
- As one continuous piece; in short, discontinuous fragments
- By RNA polymerase; by DNA polymerase
- Without a primer; with many primers
Answer: As one continuous piece; in short, discontinuous fragments
9. The short, discontinuous pieces of DNA synthesized on the lagging strand are known as:
- Klenow fragments
- Watson-Crick fragments
- Okazaki fragments
- Sanger fragments
Answer: Okazaki fragments
10. Which enzyme creates the final phosphodiester bond to join the Okazaki fragments into a continuous strand?
- DNA Polymerase
- Helicase
- Topoisomerase
- DNA Ligase
Answer: DNA Ligase
11. In E. coli, the main replicative enzyme with high processivity and proofreading ability is:
- DNA Polymerase I
- DNA Polymerase II
- DNA Polymerase III
- Taq Polymerase
Answer: DNA Polymerase III
12. The primary role of DNA Polymerase I in prokaryotic replication is:
- To synthesize the entire leading strand.
- To unwind the DNA at the origin.
- To remove the RNA primers and replace them with DNA.
- To join the Okazaki fragments.
Answer: To remove the RNA primers and replace them with DNA.
13. DNA gyrase is a unique Type II topoisomerase found in prokaryotes that:
- Introduces negative supercoils into the DNA.
- Is the primary target for fluoroquinolone antibiotics.
- Relieves the positive supercoiling ahead of the replication fork.
- All of the above.
Answer: All of the above.
14. The main replicative DNA polymerases in eukaryotes for the leading and lagging strands are:
- Polymerase α and β
- Polymerase γ
- Polymerase δ and ε
- Polymerase I and III
Answer: Polymerase δ and ε
15. In eukaryotes, the RNA primers are primarily removed by the combined action of:
- DNA Polymerase I.
- Telomerase.
- RNase H and FEN1.
- Primase and Helicase.
Answer: RNase H and FEN1.
16. The “end replication problem” is a challenge faced only by eukaryotes because:
- They have circular chromosomes.
- Their linear chromosomes will shorten with each round of replication due to the inability to complete the lagging strand end.
- Their DNA polymerase lacks proofreading.
- They have too many origins of replication.
Answer: Their linear chromosomes will shorten with each round of replication due to the inability to complete the lagging strand end.
17. Which specialized enzyme is responsible for solving the end replication problem in eukaryotes?
- DNA Ligase
- Topoisomerase
- DNA Polymerase α
- Telomerase
Answer: Telomerase
18. Telomerase is a ribonucleoprotein, meaning it contains both protein and an essential ________ component that serves as a template.
- DNA
- RNA
- Lipid
- Carbohydrate
Answer: RNA
19. A key challenge for eukaryotic replication that is absent in prokaryotes is the need to:
- Deal with supercoiling.
- Synthesize a lagging strand.
- Disassemble and reassemble nucleosomes (histones) as the replication fork passes.
- Use RNA primers.
Answer: Disassemble and reassemble nucleosomes (histones) as the replication fork passes.
20. Which proteins prevent the separated single strands of DNA from re-annealing at the replication fork?
- Histones
- Sliding clamps
- Single-strand binding (SSB) proteins
- DNA ligases
Answer: Single-strand binding (SSB) proteins
21. The protein that acts as a “sliding clamp” to increase the processivity of the main DNA polymerase in eukaryotes is known as:
- SSB
- Helicase
- PCNA (Proliferating Cell Nuclear Antigen)
- Gyrase
Answer: PCNA (Proliferating Cell Nuclear Antigen)
22. A key difference in the speed of replication is that:
- Eukaryotic replication is much faster than prokaryotic replication.
- Prokaryotic replication is much faster than eukaryotic replication.
- They both occur at the exact same speed.
- Speed is determined by the size of the chromosome only.
Answer: Prokaryotic replication is much faster than eukaryotic replication.
23. The proofreading ability of DNA polymerases, which removes mismatched bases, is due to its:
- 5′ to 3′ polymerase activity.
- 3′ to 5′ exonuclease activity.
- Helicase activity.
- Ligase activity.
Answer: 3′ to 5′ exonuclease activity.
24. The function of the DnaA protein in prokaryotic replication is to:
- Bind to the origin of replication (oriC) and initiate the unwinding of the DNA.
- Act as the primary helicase.
- Synthesize the RNA primers.
- Join the final DNA strands together.
Answer: Bind to the origin of replication (oriC) and initiate the unwinding of the DNA.
25. In eukaryotes, the initiation of replication is a highly regulated process that is tightly linked to the:
- Process of transcription.
- Cell cycle.
- Availability of nutrients.
- Time of day.
Answer: The cell cycle.
26. A pharmacist’s knowledge of the differences between prokaryotic and eukaryotic replication enzymes is critical for understanding:
- The selective toxicity of antimicrobial and anticancer drugs.
- How to manage a pharmacy’s budget.
- The principles of drug marketing.
- The legal requirements for dispensing.
Answer: The selective toxicity of antimicrobial and anticancer drugs.
27. Fluoroquinolone antibiotics are effective because they selectively inhibit:
- Human topoisomerases.
- Bacterial DNA gyrase.
- The eukaryotic sliding clamp protein PCNA.
- Telomerase.
Answer: Bacterial DNA gyrase.
28. Many chemotherapeutic agents work by targeting enzymes of DNA metabolism. A drug that targets eukaryotic topoisomerases would be a(n):
- Antibiotic.
- Anticancer agent.
- Antiviral.
- Antifungal.
Answer: Anticancer agent.
29. The “origin recognition complex” (ORC) is a protein complex that binds to origins of replication in:
- Bacteria.
- Viruses.
- Eukaryotes.
- All forms of life.
Answer: Eukaryotes.
30. The “fidelity” of DNA replication refers to its:
- Speed.
- Accuracy.
- Processivity.
- Cost-effectiveness.
Answer: Accuracy.
31. In eukaryotic replication, the polymerase that associates with primase to synthesize the RNA-DNA primer is:
- Polymerase δ
- Polymerase ε
- Polymerase α
- Polymerase γ
Answer: Polymerase α
32. The enzyme primarily responsible for replicating the mitochondrial genome in eukaryotes is:
- Polymerase δ
- Polymerase ε
- Polymerase α
- Polymerase γ
Answer: Polymerase γ
33. What is a key difference between the primers used in prokaryotic vs. eukaryotic replication?
- Prokaryotic primers are made of DNA.
- Eukaryotic primers are made of DNA.
- The length and exact composition of the primers can differ, but both are fundamentally RNA.
- Eukaryotes do not require primers.
Answer: The length and exact composition of the primers can differ, but both are fundamentally RNA.
34. The process of “termination” of replication in prokaryotes with a circular chromosome involves:
- The two replication forks simply falling off the end.
- The action of telomerase.
- Specific termination sequences (Ter sites) and the Tus protein.
- The action of DNA Polymerase I only.
Answer: Specific termination sequences (Ter sites) and the Tus protein.
35. Termination of replication in eukaryotes is more complex due to:
- The circular nature of the chromosomes.
- The presence of multiple replication forks on linear chromosomes that eventually meet.
- A single termination site on each chromosome.
- The lack of a lagging strand.
Answer: The presence of multiple replication forks on linear chromosomes that eventually meet.
36. A key part of the “Business Plan” for a biotech company developing a new antibiotic that targets DNA replication would be:
- Evidence of its selective toxicity for the prokaryotic enzyme over the eukaryotic counterpart.
- The marketing plan for the drug.
- The financial projections.
- All of the above.
Answer: All of the above.
37. The “forging ahead” mindset in pharmacy means embracing new therapies like gene editing (CRISPR), which relies on an understanding of:
- DNA repair and replication machinery.
- Marketing principles.
- Financial management.
- Human resources.
Answer: DNA repair and replication machinery.
38. A “leader” in a pharmaceutical research lab would need to guide a team through the complex process of:
- Identifying and validating a new enzyme in DNA replication as a drug target.
- Managing the lab’s budget.
- Creating a positive and collaborative work environment.
- All of the above.
Answer: All of the above.
39. The “regulation” of a new chemotherapeutic that inhibits DNA polymerase is the responsibility of the:
- DEA.
- FDA.
- CMS.
- EPA.
Answer: The FDA.
40. A “Clinical Decision Support” system could be designed to alert a pharmacist if a patient with a known __________ deficiency is prescribed a drug that is known to cause DNA damage.
- G6PD
- DNA repair enzyme
- CYP2D6
- Aldehyde dehydrogenase
Answer: DNA repair enzyme
41. The use of “analytics and reporting systems” in a large genomic study could be used to:
- Identify new mutations in DNA replication enzymes across a population.
- Track the use of antibiotics.
- Manage a hospital’s formulary.
- Report medication errors.
Answer: Identify new mutations in DNA replication enzymes across a population.
42. A key “human factors” consideration in the high-stakes process of preparing a chemotherapy drug that targets DNA replication is:
- Minimizing distractions to prevent calculation or compounding errors.
- The color of the drug.
- The brand name of the drug.
- The time of day the drug is made.
Answer: Minimizing distractions to prevent calculation or compounding errors.
43. A “negotiation” with a payer for a new, expensive anticancer drug that targets DNA replication would require a strong case based on:
- Evidence of improved patient survival from clinical trials.
- The drug’s high cost.
- The novelty of its mechanism alone.
- The personal preference of the oncologist.
Answer: Evidence of improved patient survival from clinical trials.
44. A pharmacist’s knowledge of “DNA structure” is the foundation for understanding how:
- The replication machinery interacts with the template strands.
- To manage a pharmacy’s finances.
- To counsel a patient on an inhaler.
- To run a business.
Answer: The replication machinery interacts with the template strands.
45. The “cloning” of a gene into a plasmid relies on the plasmid having a(n) _________ so that it can be replicated by the host bacterium.
- Promoter
- Antibiotic resistance gene
- Origin of replication
- Restriction site
Answer: Origin of replication
46. Which of the following is a key difference between eukaryotic and prokaryotic DNA polymerase?
- Eukaryotes have a much larger number of different DNA polymerases with specialized functions.
- Prokaryotic polymerases are less accurate.
- Eukaryotic polymerases do not require a primer.
- Prokaryotic polymerases synthesize DNA in the 3′ to 5′ direction.
Answer: Eukaryotes have a much larger number of different DNA polymerases with specialized functions.
47. Histone “chaperones” are proteins involved in eukaryotic replication that:
- Help to correctly reassemble the histone octamers on the newly synthesized DNA.
- Synthesize the RNA primers.
- Unwind the DNA.
- Join the Okazaki fragments.
Answer: Help to correctly reassemble the histone octamers on the newly synthesized DNA.
48. The high processivity of the main replicative polymerases is due to their interaction with:
- The RNA primer.
- The sliding clamp protein.
- Helicase.
- SSB proteins.
Answer: The sliding clamp protein.
49. An “antidote” for a chemotherapeutic agent that targets DNA replication would most likely work by:
- Binding directly to the drug.
- Bypassing the metabolic block or replenishing a depleted substrate (e.g., leucovorin for methotrexate).
- Inhibiting the drug’s metabolism.
- There are generally no direct antidotes for this class of drugs.
Answer: Bypassing the metabolic block or replenishing a depleted substrate (e.g., leucovorin for methotrexate).
50. The ultimate principle of why we study DNA replication in pharmacy is that:
- It is the fundamental process that allows cells to divide, making its enzymes prime targets for antimicrobial and anticancer drugs.
- It is an interesting but clinically irrelevant topic.
- It is only important for understanding genetic diseases.
- It helps in the marketing of new medications.
Answer: It is the fundamental process that allows cells to divide, making its enzymes prime targets for antimicrobial and anticancer drugs.
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com