Lecture21-DNAReplicationRepair_BCH100-S10

Lecture21-DNAReplicationRepair_BCH100-S10 - BCH 100, Spring...

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BCH 100, Spring 2010 LEC 21, DNA Replication and Repair (Dr. Ziegler) 1 BIOCHEMISTRY 100 Spring 2010 M. Ziegler Lecture 21 DNA SYNTHESIS AND REPAIR Reading: Tymoczko et al., Chapter 32 pp. 511-513, and Chapters 33 and 34 (pp. 520-545) Learning Objectives 1. Terminology : “factory model”, replisome, origin of replication, replication fork, template, direction of DNA strand synthesis, supercoiled DNA, topoisomerase, processivity, leading strand, lagging strand, proofreading, exonuclease, endonuclease, telomere, telomerase 2. Explain the term “semiconservative replication”. 3. List 5 “tasks” the DNA replication machinery must carry out. 4. Describe the role(s) of each of the main components of the protein “factory” involved in DNA replication in E. coli : 1) DnaA (initiation protein) 6) Sliding clamp 2) Helicase 7) Primase 3) SS binding protein 8) DNA polymerase I 4) DNA gyrase 9) DNA ligase 5) DNA polymerase III
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BCH 100, Spring 2010 LEC 21, DNA Replication and Repair (Dr. Ziegler) 2 Learning Objectives, continued 5. Outline how DNA polymerase III functions in E. coli , including the substrates and products of the polymerization reaction, what the enzyme requires for activity, and its proofreading activity. 6. Explain how “primer” RNA sequences are removed and nicks sealed between Okazaki fragments of lagging strand. 7. Explain the main differences between prokaryotic and eukaryotic DNA replication. 8. Explain how the 3’ end of a strand on a eukaryotic chromosome can be copied without losing any genetic information. 9. Name three kinds of damage to DNA that biochemical repair systems can fix. 10. Explain the probable reason that DNA evolved to use thymine rather than uracil to base-pair with adenine. 11. Outline the steps in nucleotide excision repair. Lecture #21 DNA SYNTHESIS AND REPAIR I. Features and Challenges of DNA replication II. Unwinding the double helix III. Synthesizing DNA IV. Proofreading V. Replication in eukaryotes VI. Repair of existing DNA
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BCH 100, Spring 2010 LEC 21, DNA Replication and Repair (Dr. Ziegler) 3 Synthesis of Macromolecules: General Principles 1. Each macromolecule contains a limited number of monomer types: DNA, RNA: 4 bases Proteins: 20 amino acids 2. Synthesis is one monomer at a time. 3. Synthesis is in a specific direction. 4. Synthesis has a specific starting and stopping point. 5. The primary product may be modified: DNA: methylation, acetylation RNA: splicing, base modification, capping, polyadenylylation Protein: cleavage, R-group modification (Conservative replication would have a first generation of 1 all-blue duplex and 1 all-red duplex.) The Meselson-Stahl Experiment (1958): DNA Replication is Semiconservative Franklin Stahl Matthew Meselson (blue) (new DNA strands red) Tymoczko et al. , Fig. 32-14
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BCH 100, Spring 2010 LEC 21, DNA Replication and Repair (Dr. Ziegler)
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Lecture21-DNAReplicationRepair_BCH100-S10 - BCH 100, Spring...

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