Chapter 18_Lecture_Pt 2

Genetics: A Conceptual Approach

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Chapter 18- Part II DNA Repair Dr. Ed Otto George Mason University
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Key objectives Discuss different repair pathways that remove damage from DNA
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DNA Repair DNA is under constant assault from radiation, chemical mutagens, and spontaneous arising changes However, the rate of mutation is remarkably low, thanks to the efficiency of DNA repair <1/1000 lesions is estimated to become a mutation; all others are corrected by repair systems
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DNA Repair There are several complex pathways for repairing DNA Two general features of DNA repair: 1.Most repair pathways require two nucleotide stands of DNA because they replace nucleotides, and a template strand is needed to specify the base sequence 1. Redundancy: many types of DNA damage can be corrected by more than one pathway of repair
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DNA Repair Four mechanisms of DNA repair: 1.Mismatch repair 1.Direct repair 1.Base-excision repair 1.Nucleotide-excision repair
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1. Mismatch Repair During replication, mismatched bases are incorporated into new DNA at a frequency of about 10 -4 to 10 -5 - These incorporation errors are caused by DNA polymerases, wobble, tautomeric shifts However, the overall error rate during DNA replication is 10 -9 because systems exist to remove
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This note was uploaded on 05/06/2010 for the course BIO 311 taught by Professor Otto during the Spring '10 term at George Mason.

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Chapter 18_Lecture_Pt 2 - Chapter 18- Part II DNA Repair...

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