DNA replication

• In which phase of the cell cycle does DNA replication occur?

  S phase
• DNA replication is described as being semi conservative
• In semiconservative DNA replication, one strand of the daughter DNA is from the parental DNA, and the other is newly synthesized.
• What are the four nitrogenous bases in DNA?

  Adenine, cytosine, guanine, thymine
• Adenine pairs only with thymine
• Match the complementary base pairs:

  Adenine ↔️ Thymine

  Cytosine ↔️ Guanine
• Why is complementary base pairing important in DNA replication?

  Reduces copying errors
• DNA helicase breaks hydrogen bonds between complementary bases in the parental DNA.
• The enzyme DNA helicase causes the double helix to unwind
• What role do free-floating DNA nucleotides play in DNA replication?

  Align opposite template strands
• Which type of bond is formed between adjacent nucleotides in a DNA strand?

  Phosphodiester bond
• DNA polymerase catalyzes the formation of phosphodiester bonds
• DNA polymerase creates a new DNA strand from the 5' end to the 3' end.
• Steps in DNA replication

  1️⃣ DNA helicase breaks hydrogen bonds

  2️⃣ Double helix unwinds

  3️⃣ Template strands are exposed

  4️⃣ Free-floating DNA nucleotides align

  5️⃣ DNA polymerase joins nucleotides
• What is the end result of DNA replication in terms of the DNA strands created?

  Two identical daughter DNA
• Which experiment proved that DNA replication is semi-conservative?

  Meselson and Stahl