DNA Replication Mechanism Quiz
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Questions and Answers

Where does DNA replication occur in prokaryotes and eukaryotes?

  • In the nucleus for both prokaryotes and eukaryotes
  • In the cytoplasm for prokaryotes and in the nucleus for eukaryotes (correct)
  • In the nucleus for prokaryotes and in the cytoplasm for eukaryotes
  • In the cytoplasm for both prokaryotes and eukaryotes

    • What is the main implication of the Watson and Crick DNA model for replication?

  • Combine the DNA strands together
  • Separate the 2 strands
  • Unwind the DNA molecule
  • Make a complementary copy for each strand (correct)

    • Which model of DNA replication involves separating the two strands and making a complementary copy for each strand?

  • Conservative model
  • Combination model
  • Dispersive model
  • Semiconservative model (correct)

    • What is the result of DNA replication in terms of the old and new DNA strands?

    <p>Both strands of one copy would be entirely old DNA, while the other copy would have both strands of new DNA</p> Signup and view all the answers

    What was the outcome of the Matthew Meselson & Frank Stahl experiment involving E. coli cultured in 15N and 14N mediums?

    <p>DNA replicated with a mixture of 15N and 14N isotopes</p> Signup and view all the answers

    Which isotope of nitrogen is by far the most abundant?

    <p>14N</p> Signup and view all the answers

    In which step of the Matthew Meselson & Frank Stahl experiment was E. coli cultured in a 15N medium?

    <p>Step 1</p> Signup and view all the answers

    What does the term 'bidirectional' mean in the context of DNA replication?

    <p>'Bidirectional' means replication occurs in both directions along the DNA strand</p> Signup and view all the answers

    What does the term 'conservative model' propose about DNA replication?

    <p>'Conservative model' proposes that one strand of the parent molecule is conserved in each new DNA molecule</p> Signup and view all the answers

    What is the purpose of centrifuging the extracted DNA samples on a salt density gradient?

    <p>To separate DNA based on its density</p> Signup and view all the answers

    In which medium did the DNA synthesized after 1 replication cycle have a higher density?

    <p>15N containing medium</p> Signup and view all the answers

    After 2 replication cycles in a 14N medium, how many bands of DNA were observed?

    <p>2</p> Signup and view all the answers

    Which model did the Meselson-Stahl experiment not fit, and why?

    <p>Conservative model, due to the presence of a single intermediate band after one generation</p> Signup and view all the answers

    What did the dispersive model predict, and how did it compare to the observed results?

    <p>Predicted no change in DNA density over generations, but observed gradual decrease in density</p> Signup and view all the answers

    Which type of DNA replication did the data from the Meselson-Stahl experiment support?

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

    What is the purpose of using CsCl salt solution in centrifugation?

    <p>To separate DNA based on its density</p> Signup and view all the answers

    After 3 cycles in a 14N medium, how many bands of DNA were observed?

    <p>2</p> Signup and view all the answers

    "Which type of replication did the dispersive model predict, and how did it compare to the observed results?"

    <p>&quot;Predicted no change in DNA density over generations; observed gradual decrease in density&quot;</p> Signup and view all the answers

    Which of the following is NOT a proposed model for DNA replication?

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

    What is the main implication of the Watson and Crick DNA model for replication?

    <p>Make a complementary copy for each strand</p> Signup and view all the answers

    Which step of the Matthew Meselson & Frank Stahl experiment involved culturing E. coli in a 15N medium?

    <p>Step 1</p> Signup and view all the answers

    What is the result of DNA replication in terms of the old and new DNA strands?

    <p>DNA strands separate and a complementary strand is synthesized for each, so that sibling chromatids have one old and one new strand.</p> Signup and view all the answers

    What is the main implication of the Meselson-Stahl experiment?

    <p>DNA replication is conservative</p> Signup and view all the answers

    What does the dispersive model predict, and how did it compare to the observed results?

    <p>It predicted a single band of DNA of intermediate density in each generation, which was not observed</p> Signup and view all the answers

    What was the outcome of the Matthew Meselson & Frank Stahl experiment involving E. coli cultured in 15N and 14N mediums?

    <p>After 2 replication cycles in a 14N medium, there were 2 bands, one of intermediate density and one of lighter density corresponding with 14N</p> Signup and view all the answers

    What is the purpose of using CsCl salt solution in centrifugation?

    <p>To separate DNA based on its density</p> Signup and view all the answers

    Which model did the Meselson-Stahl experiment not fit, and why?

    <p>The dispersive model because it predicted a single band of DNA of intermediate density, which was not observed</p> Signup and view all the answers

    Which type of replication did the dispersive model predict, and how did it compare to the observed results?

    <p>The dispersive model predicted semi-conservative replication, but the observed results did not match this prediction</p> Signup and view all the answers

    In which medium did the DNA synthesized after 1 replication cycle have a higher density?

    <p>15N medium</p> Signup and view all the answers

    Which type of DNA replication did the data from the Meselson-Stahl experiment support?

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

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