Chapter 12.2 dna replication

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Chapter 12.2 dna replication

  1. 1. 12.2 Replication of DNA
  2. 2. Semiconservative Replication <ul><li>Semiconservative Replication- When the parental strands of DNA separate (serving as templates) and produce DNA molecules that have 1 strand of parental DNA and 1 strand of new DNA </li></ul><ul><li>DNA replication occurs during Interphase of Mitosis and Meiosis. </li></ul>
  3. 3. <ul><li>Why it is important </li></ul><ul><li>Makes duplicate copies of DNA to pass along all genetic info </li></ul><ul><li>Without replication, species could not survive </li></ul><ul><li>During replication, each strand serves as a pattern to make a new DNA molecule </li></ul>
  4. 4. 3 Stages of Semiconservative replication: Unwinding, Base Pairing, and Joining. <ul><li>Step 1: Unwinding </li></ul><ul><li>An enzyme (DNA helicase) unwinds and unzips the double helix. Hydrogen bonds are broken, leaving a leading strand and a lagging strand. </li></ul><ul><li>Single-stranded binding proteins keep the strands separated during replication. </li></ul><ul><li>RNA primase adds a short segment of RNA (RNA primer) on each strand </li></ul>
  5. 5. Leading strand- moves in the same direction as the replication fork. It replicates continuously. Lagging strand- moves in the opposite direction. It does NOT replicate continuously.
  6. 6. <ul><li>Step 2: Base Pairing </li></ul><ul><li>An enzyme (DNA polymerase) aids in adding new DNA nucleotides to the chain </li></ul><ul><li>Since A binds to T and C binds to G, an identical copy is made. </li></ul><ul><li>Okazaki fragments- Short segments of DNA which will later be connected by DNA ligase. (Lagging strand only) </li></ul>
  7. 9. <ul><li>Step 3: Joining </li></ul><ul><li>DNA polymerase comes to a RNA primer on the DNA, removes the primer, and fills in the place with DNA nucleotides. Once replaced, DNA ligase links (or zips up) the 2 sections. </li></ul>
  8. 10. http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it =swf::535::535::/sites/dl/free/0072437316/120076/micro04.swf::DNA%20Replication%20Fork DNA replication animation
  9. 11. The importance of nucleotide sequence <ul><li>The sequence of nucleotides form the unique genetic information of an organism. </li></ul><ul><li>The more closely related two organisms are, the more alike the sequence of nucleotides in the DNA will be. </li></ul><ul><li>Ex: Gel Electrophoresis </li></ul>
  10. 12. Gel Electrophoresis

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