4.2 DNA Replication

• What is the definition of DNA replication?

  Copying a parent DNA strand
• Order the key enzymes involved in DNA replication according to their primary functions.

  1️⃣ Helicase unwinds the double helix

  2️⃣ DNA Polymerase adds complementary nucleotides

  3️⃣ Primase synthesizes RNA primers

  4️⃣ Ligase seals gaps between Okazaki fragments
• DNA ligase seals the gaps between Okazaki fragments
• What is the primary role of DNA ligase in DNA replication?

  Seals gaps between Okazaki fragments
• What does the semiconservative model of DNA replication ensure?

  Faithful copying of genetic information
• Topoisomerase relieves tension ahead of helicase to prevent supercoiling of the DNA.


  True
• The lagging strand is synthesized discontinuously in the 5' to 3' direction, forming Okazaki fragments
• The leading strand is synthesized continuously in the 3' to 5' direction

  False
• The semiconservative model states that each new DNA molecule contains two original parent strands.

  False
• Helicase unwinds the DNA double helix at the replication fork
• Match the DNA strand with its synthesis method:

  Leading Strand ↔️ Continuous synthesis

  Lagging Strand ↔️ Discontinuous synthesis
• DNA Ligase joins the Okazaki fragments on the lagging strand.

  True
• DNA polymerase has a proofreading function that detects and corrects mismatched base pairs
• What are the two key error correction mechanisms in DNA replication?

  Proofreading and mismatch repair
• DNA replication is a semi-conservative process because each new molecule contains one original and one newly synthesized strand
• The semiconservative model states that each new DNA molecule contains two original parent strands.

  False
• What is the function of DNA polymerase in DNA replication?

  Adds complementary nucleotides
• Primase is responsible for synthesizing short RNA primers to initiate DNA replication.


  True
• DNA replication is called semi-conservative because each new DNA molecule contains one original and one newly synthesized strand
• Which enzyme creates a replication fork by unwinding the DNA double helix?

  Helicase
• How is the leading strand synthesized during DNA replication?

  Continuously in the 5' to 3' direction
• The unwinding and separation of DNA strands during replication creates a replication fork
• Match the enzyme with its function in DNA replication:

  DNA Polymerase ↔️ Synthesizes new DNA strands

  Primase ↔️ Creates RNA primers

  DNA Ligase ↔️ Joins Okazaki fragments
• DNA replication is a semi-conservative process, meaning each new molecule contains one original and one newly synthesized strand
• Steps in the synthesis of the lagging strand:

  1️⃣ Helicase unwinds the DNA

  2️⃣ Primase creates RNA primers

  3️⃣ DNA Polymerase adds nucleotides

  4️⃣ DNA Ligase joins Okazaki fragments
• Topoisomerase relieves tension ahead of the helicase to prevent supercoiling.


  True
• The lagging strand's discontinuous synthesis results in short segments called Okazaki fragments
• Match the enzyme with its function in DNA replication:

  DNA Polymerase ↔️ Adds nucleotides to DNA

  DNA Ligase ↔️ Joins Okazaki fragments
• Mismatch repair enzymes correct errors after replication is complete.

  True
• DNA polymerase has a proofreading function that can detect and correct mismatched base pairs as it adds nucleotides
• Which enzymes correct errors that escape proofreading during DNA replication?

  Mismatch repair enzymes
• Error correction mechanisms in DNA replication work together to minimize mutations and preserve genetic integrity.

  True
• DNA replication is a semi-conservative process because each new DNA molecule contains one original and one newly synthesized strand
• The semiconservative model states that each new DNA molecule contains two newly synthesized strands.

  False
• What is the role of the parent strand in the semiconservative model?

  Serves as a template
• Which enzyme creates a replication fork by unwinding the DNA double helix?

  Helicase
• Order the steps involved in DNA replication according to enzyme function:

  1️⃣ Helicase unwinds the DNA double helix

  2️⃣ Primase synthesizes RNA primers

  3️⃣ DNA polymerase adds nucleotides

  4️⃣ Ligase seals Okazaki fragments
• During DNA replication, the leading strand is synthesized continuously in the 5' to 3' direction
• What is the role of topoisomerase during DNA replication?

  Reduces DNA supercoiling
• DNA replication begins at a replication fork