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DNA Replication

DNA Replication . DNA Replication Facts. DNA Replication: DNA = Only known molecule that can replicate itself Structure explains how it easily replicates Each molecule has information needed to reconstruct the other side

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DNA Replication

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  1. DNA Replication

  2. DNA Replication Facts • DNA Replication: • DNA = • Only known molecule that can replicate itself • Structure explains how it easily replicates • Each molecule has information needed to reconstruct the other side • DNA molecules separates into 2 strands & produces 2 new identical strands (follows base pair rules) • DNA serves as model for new DNA strands

  3. DNA Replication Facts cont. • DNA Replication cont. • Occurs in S (Synthesis) phase of cell cycle • Chromosome #’s are being doubled = DNA is being replicated • Genetic material is going from 1 copy to 2 copies • Each new daughter cell will have exact same copy of DNA • Very rapid & accurate (only 1 in 1 Billion base-pairing errors) process

  4. DNA Replication • Process of DNA Replication: • Begins at Origins of Replication • Enzyme Helicase unwinds & separates 2 DNA strands – breaks the weak hydrogen bonds • Single-Strand Binding Proteins attach & keep 2 DNA strands separated & untwisted • 2 strands open forming Replication Forks (Y-shaped) • New strands grow at the forks

  5. DNA Replication cont. • Process of DNA Replication cont: • RNA Primers add new nucleotides to help form new DNA strands • Correct bases are added to each side of the backbone (ladder) • A -- T & C -- G • Sugar-phosphate backbone links are added to extend the backbone (ladder)

  6. DNA Replication cont. • Proofreading the new DNA: • Enzyme - DNA polymerase proofreads new DNA strand to make sure base pairing is correct • If error is found – polymerase will cut, remove & correct the mistake = Excision Repair • Error rate after proofreading = 1 in 1 billion base pairing errors • Now have 2 identical DNA strands!!

  7. DNA Template Parental DNA Molecule Replication Fork Parental DNA RNA Primer New DNA DNA Polymerase Nucleotides DNA Replication (Draw these!) Helicase S.S.B.P

  8. DNA Replication Review • DNA Replication Review: • DNA is unzipped (by Helicase) • DNA strands held open by (Single-Stranded Binding Proteins) • RNA Primers add new nucleotides • Sugar-phosphate links are added • DNA polymerase proofreads new DNA strands • Fixes any errors = Excision Repair • Two new identical DNA strands

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