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DNA Replication quiz #1

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  • What does it mean that DNA replication is semi-conservative, and how does this process ensure genetic continuity?
    DNA replication is semi-conservative, meaning each new DNA molecule consists of one original (parental) strand and one newly synthesized strand. This ensures genetic continuity by preserving half of the original DNA in each daughter molecule, reducing the chance of errors being passed on.
  • Describe the roles of DNA polymerase, primase, helicase, and ligase during DNA replication.
    DNA polymerase synthesizes new DNA strands in the 5' to 3' direction; primase creates short RNA primers to provide a starting point for DNA polymerase; helicase unwinds the DNA double helix; and ligase joins Okazaki fragments on the lagging strand to form a continuous DNA strand.
  • Why are telomeres and the enzyme telomerase important for the replication of linear chromosomes in eukaryotic cells?
    Telomeres are repetitive, non-coding DNA sequences at chromosome ends that protect coding regions from degradation. Telomerase extends telomeres, allowing complete replication of the lagging strand and preventing loss of essential genetic information during cell division.
  • How does DNA polymerase proofread newly synthesized DNA, and what is the significance of its 3' to 5' exonuclease activity?
    DNA polymerase proofreads by checking each newly added nucleotide; if a mismatch is detected, its 3' to 5' exonuclease activity removes the incorrect base, allowing the correct one to be inserted. This proofreading greatly increases the fidelity of DNA replication.
  • What does it mean that DNA replication is semi-conservative, and how does this process ensure genetic continuity?
    DNA replication is semi-conservative, meaning each new DNA molecule contains one original (parental) strand and one newly synthesized strand. This preserves half of the original DNA in each daughter molecule, reducing the chance of errors being passed on.
  • Describe the roles of DNA polymerase, primase, helicase, and ligase during DNA replication.
    DNA polymerase synthesizes new DNA strands in the 5' to 3' direction; primase creates short RNA primers to provide a starting point for DNA polymerase; helicase unwinds the DNA double helix; and ligase joins Okazaki fragments on the lagging strand to form a continuous DNA strand.
  • Why are telomeres and the enzyme telomerase important for the replication of linear chromosomes in eukaryotic cells?
    Telomeres are repetitive, non-coding DNA sequences at chromosome ends that protect coding regions from degradation. Telomerase extends telomeres, allowing complete replication of the lagging strand and preventing loss of essential genetic information during cell division.
  • How does DNA polymerase proofread newly synthesized DNA, and what is the significance of its 3' to 5' exonuclease activity?
    DNA polymerase proofreads by checking each newly added nucleotide; if a mismatch is detected, its 3' to 5' exonuclease activity removes the incorrect base, allowing the correct one to be inserted. This proofreading greatly increases the fidelity of DNA replication.
  • What is the difference between the synthesis of the leading and lagging strands during DNA replication?
    The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously as Okazaki fragments, which are later joined together by DNA ligase.
  • Why can new nucleotides only be added to the 3' end of a growing DNA strand during replication?
    New nucleotides can only be added to the 3' end because the 3' hydroxyl group attacks the phosphate group of the incoming dNTP, releasing energy needed for bond formation. The 5' end cannot participate in this reaction, so elongation only occurs at the 3' end.
  • What is the process called by which a cell copies its DNA before cell division?
    DNA replication.
  • What occurs during the S phase of the cell cycle?
    DNA replication occurs, resulting in the duplication of chromosomes.
  • During which portion of the cell cycle are chromosomes duplicated?
    Chromosomes are duplicated during the S phase of interphase.
  • In which phase of the cell cycle does DNA replication take place?
    DNA replication takes place during the S phase of the cell cycle.
  • What happens in the S phase of the cell cycle?
    The cell replicates its DNA, resulting in the duplication of chromosomes.
  • At what stage of the cell cycle is DNA replicated?
    DNA is replicated during the S phase of the cell cycle.
  • When does DNA replication occur in the cell cycle?
    DNA replication occurs during the S phase of the cell cycle.
  • During which stage of the cell cycle are chromosomes duplicated?
    Chromosomes are duplicated during the S phase of interphase.
  • Are chromosomes duplicated during interphase or mitosis?
    Chromosomes are duplicated during interphase, specifically in the S phase.
  • During what phase of the cell cycle is DNA replicated?
    DNA is replicated during the S phase of the cell cycle.
  • When is DNA replicated during the cell cycle?
    DNA is replicated during the S phase of the cell cycle.
  • What does a cell copy during DNA replication?
    A cell copies its entire DNA, resulting in duplicated chromosomes.
  • What happens in the S phase of the cell cycle?
    The cell's DNA is replicated, doubling the genetic material.
  • Which phase of the cell cycle is DNA replicated?
    DNA is replicated during the S phase.
  • In what phase of mitosis do chromosomes duplicate?
    Chromosomes are duplicated before mitosis, during the S phase of interphase.
  • During which phase of the cell cycle does DNA replicate?
    DNA replicates during the S phase of the cell cycle.
  • In which phase of the cell cycle is DNA replicated?
    DNA is replicated in the S phase of the cell cycle.
  • Are chromosomes duplicated before or during mitosis?
    Chromosomes are duplicated before mitosis, during the S phase of interphase.
  • During which part of cell division is DNA replicated?
    DNA is replicated during the S phase of interphase, before cell division.
  • In which phase is DNA replicated in relation to mitosis?
    DNA is replicated before mitosis, during the S phase of interphase.
  • During which phase of the cell cycle is DNA replicated?
    DNA is replicated during the S phase of the cell cycle.
  • During which phase of the cell cycle are chromosomes duplicated?
    Chromosomes are duplicated during the S phase of the cell cycle.
  • During which phase of the cell cycle are chromosomes duplicated?
    Chromosomes are duplicated during the S phase of the cell cycle.
  • During which stage of the cell cycle is DNA copied?
    DNA is copied during the S phase of the cell cycle.
  • During which phase of the cell cycle are chromosomes replicated?
    Chromosomes are replicated during the S phase of the cell cycle.
  • Which process must occur before mitosis and meiosis can occur?
    DNA replication must occur before mitosis and meiosis.
  • DNA replication occurs during which phase of the cell cycle?
    DNA replication occurs during the S phase of the cell cycle.
  • Name the cell cycle phase during which DNA replication occurs.
    DNA replication occurs during the S phase.
  • What needs to be duplicated before cell division?
    The cell's DNA (chromosomes) needs to be duplicated before cell division.
  • During which phase of mitosis is DNA replicated?
    DNA is not replicated during mitosis; it is replicated before mitosis, during the S phase of interphase.