W3L5 - DNA replication MCQ

• Which enzyme unwinds the parental DNA molecule by breaking the hydrogen bonds that hold the two strands together?

  1. DNA helicase
  2. DNA polymerase
  3. DNA primase
  4. single-stranded binding protein, SSB
  5. topoisomerases

  1
• Because DNA polymerase III can only act from 5' to 3', continuous strand growth can be achieved only along one of the template strands (leading strand), and strand growth along the other strand must occur discontinuously resulting in the production of a series of short sections of new DNA. What are these sections called?

  1. Klenow fragments
  2. None of the above
  3. Okazaki fragments
  4. Replicon fragments

  3
• Replication occurs once every cell generation during?

  1. A phase
  2. C phase
  3. S phase
  4. T phase

  3
• Most of the mistakes during DNA replication are corrected by?

  1. DNA helicase
  2. DNA ligase
  3. DNA polymerase III
  4. DNA primase
  5. topoisomerases

  3
• Which of the following enzymes joins Okazaki fragments?

  1. DNA helicase
  2. DNA ligase
  3. DNA polymerase I
  4. DNA polymerase III
  5. topoisomerases

  2
• Because of the antiparallel nature of the DNA double helix, the direction of DNA synthesis for leading and lagging strand are opposite. Because of this, the two DNA polymerase molecules involved physically move in opposite directions. Is this true or false?

  false
• DNA topoisomerases?

  1. correct replication errors
  2. ligate Okazaki fragments
  3. relieve supercoils that accumulate behind active replication forks
  4. relieve supercoils that accumulate in front of active replication forks
  5. unwind the parental DNA

  4
• DNA polymerase III builds new strands from scratch during DNA replication. True or False?

  False - DNA polymerase III does not build new strands from scratch during DNA replication. Hence, this is false.
• DNA replication is said to be semiconservative because:

  1. a new double helix contains one old and one new strand
  2. both RNA and DNA synthesis are involved in the process
  3. each new strand is complementary, not identical, to its template
  4. part of the telomere, the ends of chromosomes, is lost during each round of replication

  1
• Why is an RNA primer necessary for DNA replication?

  1. DNA polymerase can only add nucleotides to RNA molecules
  2. DNA polymerase can only add nucleotides to an existing strand
  3. The RNA primer creates the 5' and 3' ends of the strand
  4. The RNA primer is necessary for the activity of DNA ligase

  2