DNA Replication

Question 1

Direction of Synthesis

Answer 1

DNA synthesis proceeds in a 5’ to 3’ direction
Template & the newly synthesized strands are antiparallel

Question 2

Initiation

Answer 2

• Initiator protein binds to Origin of
  Replication
• Helicase unwinds the helix; 2 replication forks formed
• Single-strand binding proteins keep the DNA helix open
• Primase synthesizes RNA primer
• Primers are complementary & antiparallel to each template strand

Question 3

Elongation

Answer 3

• Correct nucleotide sequence copied from template strand to newly synthesized DNA strand
• DNA polymerase III catalyzes phosphodiester bond between adjacent nucleotides
• Leading strand has continuous DNA synthesis
• Lagging strand has discontinuous DNA synthesis
• Okazaki fragment: short DNA fragments on lagging strand
  DNA polymerase I replaces RNA primer with DNA sequence
  DNA ligase covalently joins successive Okazaki fragments together