DNA Replication

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DNA Replication

• Nancy G. Morris
• Volunteer State Community College

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DNA - The Immortal Thread

• DNA stores information for development and
  metabolism.
• DNA is capable of self-duplicating exact copies
  of itself in a process called replication.
• Modifications to the genome occur as a result of
  mutation.

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DNA - The Immortal Thread

• Enzymes and other materials within the cell are
  required for replication.
• This is the hereditary link with past ancestry
  and future progeny.

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14.6 Review DNA structure
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Watson and Crick Model

• Double helix with sugar-phosphate backbone
  paired bases inside.
• Bases are specifically paired. Amount of AT and
  CG.

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DNA Replication -- overview

• DNA molecule unwinds from its helix revealing the
  two backbones which form the DNA ladder.
• The ladder is unzipped -- weak hydrogen bonds
  between the paired nitrogen bases break.
• Synthesis begins with each strand acting as a
  template to which complimentary nucleotides are
  matched.

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DNA Replication -- overview

• Polymerization of the DNA molecules happens
  simultaneously on each strand.
• The two resulting DNA molecules (daughter
  molecules) contain 1/2 the original DNA and 1/2
  the newly synthesized DNA. This is
  semi-conservative replication.
• Figure 14.7

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DNA Synthesis
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Summary of Replication (page 228)
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Replication Enzymes

• Unwinding Helicase
• Prevention of supercoiling Topoisomerase
• Stabilizing unwound DNA binding proteins
  
• Addition of nucleotides DNA Polymerase
• RNA primers on lagging strand Primase
• Bonding Okazaki Fragments DNA Ligase

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Molecular basis for sickle-cell anemia