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DNA Replication
Episode 1062nd June 2021 • My AP Biology Thoughts • Hopewell Valley Student Publications Network
00:00:00 00:05:05

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My AP Biology Thoughts  

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode # 106 called Unit 6 Gene Expression and Regulation: DNA Replication. Today we will be discussing the process by which cells replicate their DNA

Segment 1: Introduction to DNA Replication

  •  Difference between prokaryotic and Eukaryotic DNA
  • P is one circular piece of dna where eukaryotic are multiple linear chromosomes
  • DNA replication is semi-conservative
  • Double helix is split in two and then each new strand is synthesized so to new double helices are made, each with one old and one new strand 
  • very complex but very fast
  • Extremely accurate (only 1 in a billion bases are messed up)
  • Have to prime the DNA for replication
  • Primers are short molecules that attach to the dna at the origin of replication 
  • Mde by the enzyme primase
  • Helicase is the enzyme that unwinds the double helix- initiates the replication fork (where two strands split apart)
  • Multiple replication forks in eukaryotic dna
  • Topoisomerase checks problems in the DNA before replication and maintains the structure
  • DNA polymerase is the enzyme that synthesizes the new DNA strand- reads the bases and matches up complementary nucleotides

Segment 2: More About the process of replication

  •  Replication initiation can occur at both directions from the origin where the primer binds
  • DNA polymerase can only add nucleotides in the 5 to 3 prime direction, and read the strand of dna in the 3 to 5 prime direction
  • Leading strand is continuous
  • Lagging strand is discontinuous, has to read and synthesize in short segments (okazaki fragments)
  • Enzyme ligase seals together the fragments
  • Energy needed for this process (remember forming bonds between the nucleotides requires energy) 

Segment 3: Connection to the Course

  •  Connection to mitosis
  • S phase of mitosis is dna replication
  • Necessary for cell division to make the same amount of chromosomes in daughter cells
  • Process is close to the same for rna synthesis
  • Leading and lagging strands
  • Okazaki fragments and 3 to 5 prime direction vs 5 to 3 prime direction

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit

Music Credits:

  • "Ice Flow" Kevin MacLeod (
  • Licensed under Creative Commons: By Attribution 4.0 License

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