DNA structure and Replication

DNA structure and Replication - Replicating the Ends of DNA...

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BIOL K101 Chapter 16 Outline DNA Structure and Replication DNA Structure Discovery of DNA Structure Sugar-Phosphate backbone Nitrogenous bases Adenine (A) Guanine (G) Thymine (T) Cytosine (C) Double strand Double helix DNA Replication New strand formed using the template and DNA polymerase and other enzymes Semi-conservative replication Origins of Replication DNA helix unwinds and “unzips” Helicase Single Strand Binding Proteins Topoisomerase Replication Bubbles (multiples) Replication Forks Leading Strand Synthesized continuously 5’-3’ DNA Polymerase III Lagging Strand Synthesized Discontinuously Away from the Replication Fork 5’-3’ Primase DNA Polymerase III Okazaki Fragments DNA Polymerase I DNA Ligase Proof Reading and Repair Error rate of 1 in 100,000 nucleotides DNA Polymerases proof read as the strand is synthesized Nuceotide Excision Repair Thymine dimmers (bases covalently link)
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Unformatted text preview: Replicating the Ends of DNA Molecules Lagging Strand has no 3 end for DNA Pol once primer is removed In second round of replication both strands are shortened Telomeres Repetitive DNA sequence at the ends TTAGGG (110-1000 times) Help protect DNA from systems that monitor DNA damage stop division or cell death Packaging of DNA Histone Proteins H2A H2B H3 H4 Positively Charged (bind to negatively charged DNA molecule) Nucleosome DNA wound twice a protein core of 2 each of the histones Linker DNA 30 nm Fiber Interaction between histone tails and linker DNA Typical of Interphase Looped Domains Attached to Chromosome Scaffolding (proteins) Topoisomerase, Histone 1 present Chromosome Euchromatin Heterochromatin- visable not available for activity...
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DNA structure and Replication - Replicating the Ends of DNA...

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