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Replication and Its Applications

Replication and Its Applications. DNA Sequencing PCR. Confirmed by Messelson-Stahl: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#. DNA Replication is semiconservative. Steps in DNA Replication.

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Replication and Its Applications

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  1. Replication and Its Applications DNA Sequencing PCR

  2. Confirmed by Messelson-Stahl: http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html# DNA Replication is semiconservative

  3. Steps in DNA Replication • Begins at specific sites called origins of replication • DNA helicase unwinds double helix by breaking H-bonds – forms replication forks • Single-stranded binding proteins hold strands open

  4. DNA polymerases add nucleotides to 3’-end of growing DNA strand Synthesis is always in 5’3’ direction Requires a RNA primer to build off of DNA primasesynthesizes a RNA primer

  5. DNA Replication occurs on both strands at the same time • Strands run in opposite directions • Therefore, only 1 strand can replicate toward the replication fork: leading strand • Strand replicating away from the fork is called the lagging strand • Can only synthesize short pieces at a time • Okazaki fragments

  6. Synthesis on leading strand is continuous Synthesis on lagging strand requires multiple primers When RNA primer of previous Okazaki fragment is reached, DNA polymerase breaks it down DNA ligase seals Okazaki fragments together http://207.207.4.198/pub/flash/24/menu.swf http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html#

  7. Proofreading • DNA polymerase proofreads new nucleotides against template • If mistake made, DNA polymerase repairs mistake • If mistake not corrected, mutation has occurred

  8. Prokaryotes have 1 origin of replication Eukaryotic chromosomes have multiple origins of replication Replication bubbles eventually meet and merge Speeds up process Pro vs. Eukaryotes

  9. Telomeres • End of each chromosome is left short, unreplicated strands of DNA • These ends are repeating, non-coding sections called telomeres • Help to regulate the # of times of cell can divide • Cancer cells possess telomerase, which adds repeating sequences to ends of chromosomes

  10. Using Replication in Biotechnology

  11. Polymerase Chain Reaction • Amplifies small amounts of DNA • Without cloning • Uses nucleotides, primers to replicate DNA sequence • http://learn.genetics.utah.edu/content/labs/pcr/ • http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter16/animations.html#

  12. DNA Sequencing • Determining the order of bases that make up the genome • Requires dideoxynucleotides (ddnt) • Stop addition of new nucleotides

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