DNA Replication Mechanisms Quiz
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Questions and Answers

Which of the following best describes the arrangement and nature of nitrogenous bases in DNA strands that allows them to serve as templates for DNA replication?

  • The nitrogenous bases are arranged in a way that allows for multiple possible pairings between the strands.
  • The nitrogenous bases are arranged in a specific order, with adenine always pairing with thymine and cytosine always pairing with guanine. (correct)
  • The nitrogenous bases are randomly arranged and have no specific pairing patterns.
  • The nitrogenous bases are arranged in a way that allows for only one possible pairing between the strands.

    • Which of the three proposed DNA replication mechanisms was supported by the Meselson-Stahl experiment in bacteria?

  • Dispersive replication
  • The Meselson-Stahl experiment did not provide evidence for any of the three proposed mechanisms.
  • Semiconservative replication (correct)
  • Conservative replication

    • What was the key experimental technique used by Meselson and Stahl to determine the mechanism of DNA replication in bacteria?

  • Electron microscopy
  • Autoradiography
  • Genetic transformation
  • Buoyant density gradient centrifugation (correct)

    • What was the significance of the Taylor-Woods-Hughes experiment in eukaryotes?

    <p>It confirmed the semiconservative model of DNA replication in eukaryotes.</p> Signup and view all the answers

    Which of the following is a key difference between DNA replication in prokaryotes and eukaryotes?

    <p>The enzymes involved in DNA replication are completely different.</p> Signup and view all the answers

    What is the significance of the complementarity of DNA strands in the process of DNA replication?

    <p>It ensures that each daughter duplex contains one parental and one daughter strand.</p> Signup and view all the answers

    Which of the following is a key characteristic of the dispersive model of DNA replication?

    <p>Each daughter duplex contains interspersed parental and daughter segments.</p> Signup and view all the answers

    What was the primary purpose of the Taylor-Woods-Hughes experiment in eukaryotes?

    <p>To determine the mechanism of DNA replication in eukaryotic cells.</p> Signup and view all the answers

    What is the main function of the enzymes and proteins called replisomes during DNA replication?

    <p>They assemble at each replication fork to coordinate the replication process.</p> Signup and view all the answers

    What is the primary role of the DnaA protein during replication initiation in bacteria?

    <p>DnaA first binds the 9-mer sequences, bends the DNA, and breaks hydrogen bonds in the A-T rich sequences of the 13-mer region.</p> Signup and view all the answers

    What is the main role of the DnaB helicase during replication initiation in bacteria?

    <p>DnaB uses ATP energy to break hydrogen bonds of complementary bases and separate the DNA strands.</p> Signup and view all the answers

    What is the primary function of the single-stranded binding protein (SSB) during DNA replication in bacteria?

    <p>SSB keeps the unwound DNA strands from reannealing, preventing the double-stranded DNA from reforming.</p> Signup and view all the answers

    What is the primary role of the RNA primers during DNA replication?

    <p>RNA primers are needed because DNA polymerases cannot initiate DNA strand synthesis on their own.</p> Signup and view all the answers

    What is the primary function of the DNA polymerase I (pol I) during DNA replication in bacteria?

    <p>DNA polymerase I (pol I) uses its 5' to 3' exonuclease activity to remove RNA primers and its DNA polymerase activity to fill in the gaps.</p> Signup and view all the answers

    What is the primary function of the topoisomerase enzymes during DNA replication in bacteria?

    <p>Topoisomerases catalyze the controlled cleavage and rejoining of DNA to prevent overwinding and supercoiling of the DNA during replication.</p> Signup and view all the answers

    What is the main purpose of the origin of replication (oriC) sequence in E. coli bacteria?

    <p>The oriC sequence contains about 245 base pairs of A-T rich DNA that attracts the replication enzymes to initiate DNA replication.</p> Signup and view all the answers

    What is the purpose of the telomeres at the ends of linear chromosomes?

    <p>To protect the chromosome from improper fusion or degradation</p> Signup and view all the answers

    What is the role of telomerase in eukaryotic cells?

    <p>Both a and b</p> Signup and view all the answers

    How are newly replicated DNA molecules organized into nucleosomes?

    <p>Newly replicated DNA is organized into nucleosomes by the chromatin assembly factor 1 (CAF-1).</p> Signup and view all the answers

    What is the relationship between telomerase activity and telomere length in eukaryotic cells?

    <p>Telomerase activity is only present in stem cells and malignant cells, maintaining their telomere length.</p> Signup and view all the answers

    What is the purpose of the nucleosomes formed by the wrapping of DNA around histone proteins?

    <p>To compact the DNA and facilitate its storage within the cell nucleus.</p> Signup and view all the answers

    What is the role of PCNA (proliferating cell nuclear antigen) in the organization of newly replicated DNA?

    <p>PCNA acts as a clamp that surrounds the DNA, helping to recruit and coordinate the activities of various DNA replication enzymes.</p> Signup and view all the answers

    What is the purpose of the chromatin structure formed by the binding of DNA to histone proteins?

    <p>The chromatin structure helps to compact the DNA and regulate gene expression.</p> Signup and view all the answers

    What is the role of the CAF-1 (chromatin assembly factor 1) protein in the organization of newly replicated DNA?

    <p>CAF-1 is responsible for assembling newly replicated DNA into nucleosomes.</p> Signup and view all the answers

    What is the primary function of the origin of replication (ORI) in bacterial DNA replication?

    <p>To initiate the unwinding of the DNA double helix and create the replication fork</p> Signup and view all the answers

    In the context of bacterial DNA replication, what does the term 'bidirectional' refer to?

    <p>The simultaneous synthesis of new DNA strands in opposite directions from the replication fork</p> Signup and view all the answers

    Based on the information provided, which statement accurately describes the rate of DNA synthesis in E. coli?

    <p>DNA polymerase can incorporate approximately 1000 nucleotides per second into the new DNA strand</p> Signup and view all the answers

    What is a significant difference between DNA replication in bacteria and eukaryotes?

    <p>Eukaryotic DNA replication involves multiple origins of replication, while bacterial DNA replication has a single origin</p> Signup and view all the answers

    According to the information provided, approximately how many origins of replication are present in the human genome?

    <p>More than 10,000</p> Signup and view all the answers

    What is the purpose of having multiple origins of replication in eukaryotic chromosomes?

    <p>To increase the rate of DNA synthesis and replicate the large genome more efficiently</p> Signup and view all the answers

    Based on the information provided, what can be inferred about the relationship between the generation time of E. coli and the rate of DNA replication?

    <p>The generation time of E. coli is directly proportional to the rate of DNA replication</p> Signup and view all the answers

    What is the approximate distance between origins of replication on eukaryotic chromosomes, as stated in the information provided?

    <p>40,000 to 50,000 base pairs</p> Signup and view all the answers

    Which of the following is a function of the 5'-3' exonuclease activity of DNA polymerase III?

    <p>It removes RNA primers from the lagging strand during DNA replication.</p> Signup and view all the answers

    What is the role of the 5'-3' polymerase activity of DNA polymerase III?

    <p>It adds deoxyribonucleotides to the 3' end of the growing DNA strand.</p> Signup and view all the answers

    Which of the following is a key component of the replisome in eukaryotes?

    <p>Topoisomerase</p> Signup and view all the answers

    What is the role of the origin recognition complex (ORC) in eukaryotic DNA replication?

    <p>It recognizes and binds to the origin of replication sequences (ORI).</p> Signup and view all the answers

    What is the function of the autonomously replicating sequences (ARS) in yeast?

    <p>They are the multiple origins of replication in the yeast genome.</p> Signup and view all the answers

    Which of the following statements about eukaryotic DNA replication is correct?

    <p>Eukaryotic DNA replication involves linear chromosomes and DNA complexed with nucleosomes.</p> Signup and view all the answers

    What is the role of the helicase enzyme in eukaryotic DNA replication?

    <p>It disrupts the hydrogen bonds between the DNA strands, unwinding the double helix.</p> Signup and view all the answers

    What is the purpose of having multiple origins of replication in eukaryotic chromosomes?

    <p>It facilitates rapid synthesis of large quantities of DNA during replication.</p> Signup and view all the answers

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