DNA Replication and Cell Cycle Overview
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Questions and Answers

What occurs during the S phase of Interphase in eukaryotic cells?

  • DNA is transcribed into RNA.
  • Cell division begins.
  • Sister chromatids are separated.
  • The amount of DNA doubles. (correct)

    • Which of the following statements about prokaryotic cell division is true?

  • Prokaryotes undergo a complex interphase.
  • Prokaryotes replicate DNA during M phase.
  • Binary fission is not used by prokaryotes.
  • Prokaryotes divide without mitosis. (correct)

    • What are sister chromatids?

  • Identical copies of a chromosome joined at the centromere. (correct)
  • Chromosomes aligned at the metaphase plate.
  • Chromosomes that have undergone transcription.
  • Two chromosomes that have not replicated.

    • Which phase of the eukaryotic cell cycle flanks the S phase?

    <p>G1 and G2 phases.</p> Signup and view all the answers

    Which type of organisms has linear chromosomes?

    <p>Eukaryotes.</p> Signup and view all the answers

    Which model of DNA replication proposes that both daughter DNA strands are entirely newly synthesized?

    <p>Conservative model</p> Signup and view all the answers

    Which model describes the DNA replication process where each daughter DNA molecule consists of one parental strand and one newly synthesized strand?

    <p>Semiconservative model</p> Signup and view all the answers

    In which replication model are both daughter DNA strands composed of segments that are a mix of parental and newly synthesized DNA?

    <p>Dispersive model</p> Signup and view all the answers

    Which experiment is known for providing evidence that supports the semiconservative model of DNA replication?

    <p>Meselsohn &amp; Stahl experiment</p> Signup and view all the answers

    How does the conservative model differ in strand composition compared to the semiconservative model during DNA replication?

    <p>The conservative model keeps both strands entirely parental.</p> Signup and view all the answers

    What is the characteristic nature of the ORI site in both prokaryotes and eukaryotes?

    <p>A-T rich sequence</p> Signup and view all the answers

    How many ORI sites are present in a human's chromosomes?

    <p>10,000 ORI sites</p> Signup and view all the answers

    What is the shape of the replicon for circular bacterial DNA when viewed under an electron microscope?

    <p>Theta (Θ)</p> Signup and view all the answers

    What type of structure do eukaryotes form due to multiple ORI sites on their chromosomes during DNA replication?

    <p>Multiple replication units</p> Signup and view all the answers

    What initiator protein is responsible for binding to the ORI site in bacteria?

    <p>DNA A</p> Signup and view all the answers

    What is the role of RNA primers in DNA replication?

    <p>To provide a starting point for DNA polymerase to add nucleotides</p> Signup and view all the answers

    In which direction does DNA polymerase synthesize new DNA strands?

    <p>5' to 3'</p> Signup and view all the answers

    What type of bond does DNA polymerase use to join nucleotides together?

    <p>Phosphodiester bond</p> Signup and view all the answers

    What is the function of Primase in DNA replication?

    <p>To synthesize short RNA sequences as primers</p> Signup and view all the answers

    What is a critical requirement for DNA polymerase to add nucleotides to a chain?

    <p>An RNA primer</p> Signup and view all the answers

    What is the primary function of the RNA primer in DNA replication?

    <p>To initiate the synthesis of DNA strands</p> Signup and view all the answers

    What are the short discontinuous pieces of DNA synthesized on the lagging strand called?

    <p>Okazaki fragments</p> Signup and view all the answers

    How does the synthesis of the leading strand differ from that of the lagging strand?

    <p>The leading strand is synthesized continuously, while the lagging strand is formed in fragments.</p> Signup and view all the answers

    What enzyme is responsible for joining Okazaki fragments together on the lagging strand?

    <p>DNA ligase</p> Signup and view all the answers

    In eukaryotic cells, how long are Okazaki fragments typically?

    <p>100-200 bases</p> Signup and view all the answers

    What characterizes the bidirectional nature of DNA replication?

    <p>Each DNA strand is replicated in opposite directions from a single origin.</p> Signup and view all the answers

    What is the primary function of DNA polymerase's proofreading ability?

    <p>To correct mismatched bases</p> Signup and view all the answers

    What type of activity allows DNA polymerase to remove mismatched bases?

    <p>3' to 5' exonuclease activity</p> Signup and view all the answers

    How does DNA polymerase contribute to the accuracy of DNA replication?

    <p>By reducing the error rate to about one per billion base pairs</p> Signup and view all the answers

    In which direction does DNA polymerase proofread the newly added nucleotides?

    <p>3' to 5'</p> Signup and view all the answers

    What is the result of DNA polymerase's exonuclease activity during replication?

    <p>Correction of replication errors</p> Signup and view all the answers

    What mechanism does DNA polymerase I use to remove RNA primers during DNA replication?

    <p>5' to 3' exonuclease activity</p> Signup and view all the answers

    Which of the following actions can DNA polymerase I perform?

    <p>Remove RNA primers and add DNA nucleotides at the 3’ end</p> Signup and view all the answers

    What is the role of DNA ligase in DNA replication?

    <p>Sealing nicks between Okazaki fragments</p> Signup and view all the answers

    Which statement best describes the activity of DNA polymerase I?

    <p>It can remove RNA primers and extend DNA strands.</p> Signup and view all the answers

    How does DNA ligase contribute to the integrity of the DNA molecule?

    <p>By joining Okazaki fragments</p> Signup and view all the answers

    What is the primary role of Primase during DNA replication?

    <p>To synthesize a short RNA primer</p> Signup and view all the answers

    What is a requirement for DNA polymerase to initiate DNA synthesis?

    <p>A template DNA strand and RNA primer</p> Signup and view all the answers

    In which direction does DNA polymerase elongate the newly synthesized DNA strand?

    <p>5′ → 3′ direction</p> Signup and view all the answers

    What is the function of DNA ligase during DNA replication?

    <p>To join two DNA fragments together</p> Signup and view all the answers

    Which of the following describes the role of the RNA primer in DNA replication?

    <p>Serving as a starting point for DNA polymerase</p> Signup and view all the answers

    What is the primary enzyme responsible for DNA replication in bacteria?

    <p>DNA Polymerase III</p> Signup and view all the answers

    What is the function of the sliding clamp in DNA polymerase III?

    <p>To prevent DNA polymerase from dissociating from the DNA strand</p> Signup and view all the answers

    Which eukaryotic DNA polymerase is primarily responsible for mitochondrial DNA replication?

    <p>DNA Polymerase γ</p> Signup and view all the answers

    Which feature distinguishes eukaryotic DNA polymerases from their prokaryotic counterparts?

    <p>Eukaryotic DNA polymerases are more than a dozen types.</p> Signup and view all the answers

    What is the primary role of DNA Polymerase I during DNA replication?

    <p>Removing RNA primers and replacing them with DNA</p> Signup and view all the answers

    What is the main function of helicase during DNA replication?

    <p>Opens up the DNA at the replication fork</p> Signup and view all the answers

    Which enzyme is responsible for synthesizing RNA primers during DNA replication?

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

    What role do sliding clamps serve during DNA replication?

    <p>Hold DNA polymerase III in place</p> Signup and view all the answers

    How does topoisomerase function in DNA replication?

    <p>Prevents supercoiling in the DNA ahead of the replication fork</p> Signup and view all the answers

    Which enzyme is responsible for the final joining of DNA fragments during replication?

    <p>DNA Ligase</p> Signup and view all the answers

    What role do chromatin remodeling proteins play during DNA replication in eukaryotes?

    <p>They loosen nucleosome packing.</p> Signup and view all the answers

    What happens to nucleosomes after a segment of DNA is replicated in eukaryotic cells?

    <p>They are reassembled on the new strands.</p> Signup and view all the answers

    Which statement accurately describes nucleosomes in prokaryotic organisms?

    <p>They do not exist in bacteria.</p> Signup and view all the answers

    How are nucleosomes initially affected during the DNA replication process in eukaryotes?

    <p>They are temporarily disassembled.</p> Signup and view all the answers

    What is a unique feature of nucleosomes in eukaryotic cells compared to prokaryotic cells?

    <p>They provide structural stability for linear DNA.</p> Signup and view all the answers

    What is the primary function of telomeres in eukaryotic chromosomes?

    <p>Protecting important genetic information</p> Signup and view all the answers

    What sequence is uniquely repeated in human telomeres?

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

    Why can't DNA polymerase fully replicate the 5' ends of linear DNA?

    <p>There is no 3' end available for nucleotide addition</p> Signup and view all the answers

    What is the role of telomerase in cellular replication?

    <p>Replicating telomeres</p> Signup and view all the answers

    What happens to DNA molecules after repeated rounds of replication without telomerase activity?

    <p>They produce shorter DNA molecules with uneven ends</p> Signup and view all the answers

    What does the G1 checkpoint primarily check for?

    <p>DNA damage</p> Signup and view all the answers

    Which protein serves as a Go signal at the G2 checkpoint?

    <p>Mitosis Promoting Factor (MPF)</p> Signup and view all the answers

    What role does p53 play at the G2 checkpoint?

    <p>Serves as a Stop signal</p> Signup and view all the answers

    Which checkpoint is responsible for checking the proper segregation of replicated chromosomes?

    <p>M checkpoint</p> Signup and view all the answers

    What is a major characteristic of the G2 checkpoint's Stop signal?

    <p>It is regulated by protein levels</p> Signup and view all the answers

    What processes can cause damage to DNA?

    <p>Exposure to certain chemicals or radiation</p> Signup and view all the answers

    What is the main purpose of specialized repair mechanisms for DNA?

    <p>To correct DNA damage</p> Signup and view all the answers

    During which phase is DNA monitored closely for damage?

    <p>S phase</p> Signup and view all the answers

    What can be a result of not addressing DNA damage properly?

    <p>Cellular aging and disease development</p> Signup and view all the answers

    What might happen to DNA during replication?

    <p>It can spontaneously incur damage</p> Signup and view all the answers

    What type of modifications can lead to DNA mutations through base excision repair?

    <p>Deamination and alkylation</p> Signup and view all the answers

    What is the primary action taken in base excision repair?

    <p>Removal of the damaged base</p> Signup and view all the answers

    What is the result of deamination of base C in DNA?

    <p>Conversion of base C to base U</p> Signup and view all the answers

    Which of the following base pair conversions can result from base excision repair?

    <p>G/C to A/T</p> Signup and view all the answers

    What does spontaneous deamination lead to in DNA?

    <p>DNA mutations</p> Signup and view all the answers

    What type of DNA damage is typically caused by UV light exposure?

    <p>Pyrimidine dimers</p> Signup and view all the answers

    What consequence can occur if pyrimidine dimers are not repaired properly?

    <p>Potential mutations leading to cancer</p> Signup and view all the answers

    Which genetic condition is linked to a deficiency in the NER pathway?

    <p>Xeroderma pigmentosum</p> Signup and view all the answers

    What specific type of dimers is the most common formed by UV light?

    <p>T-T dimers</p> Signup and view all the answers

    What is the first step in the process of nucleotide excision repair (NER)?

    <p>Recognition of DNA damage</p> Signup and view all the answers

    What type of base modification can lead to DNA mutations?

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

    What base conversion occurs as a result of deamination?

    <p>C to U</p> Signup and view all the answers

    What is the main action performed in base excision repair?

    <p>Removal of the damaged base</p> Signup and view all the answers

    Which base pair conversion can result from base modifications like deamination?

    <p>G/C to A/T</p> Signup and view all the answers

    Which of the following is NOT a characteristic of base excision repair?

    <p>Prevention of all mutations</p> Signup and view all the answers

    Study Notes

    DNA Replication and the Eukaryotic Cell Cycle

    • Eukaryotic cells (animals, plants, fungi, protists) have linear chromosomes.
    • DNA replication happens during the S phase of Interphase.
    • The amount of DNA doubles during replication.
    • The S phase is flanked by the gap phases, G1 and G2.
    • Replicated chromosomes (sister chromatids) are joined at the centromere.
    • Sister chromatids separate during Anaphase of Mitosis.

    DNA Replication in Prokaryotes

    • Prokaryotic cells (bacteria, archaea) have a different cell cycle than eukaryotes.
    • Prokaryotes don't have an Interphase.
    • Prokaryotes don't have Mitosis.
    • Prokaryotes divide by Binary Fission.

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    Description

    This quiz covers the key concepts of DNA replication in both eukaryotic and prokaryotic cells. Students will explore the phases of the eukaryotic cell cycle, including the significance of the S phase and the process of mitosis. Additionally, the quiz contrasts these processes with the simpler binary fission found in prokaryotic cells.

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