September 27

September 27 - Lecture 9 DNA Repair and Recombination Recombination takes place in eukaryotic organisms during meiosis where the genes are

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September 27, 2010 - Lecture 9 DNA Repair and Recombination Recombination takes place in eukaryotic organisms during meiosis, where the genes are scrambled and divided into the genome of gametes Repair is the correction of damages Mutations and Mutagens Mutations are permanent, transmissible changes to the genetic material of a cell Mutagens are chemical compounds, UV radiation or ionizing radiation that increase the frequency of mutagens DNA Repair Proofreading by DNA polymerase Base excision repair o Base in a nucleotide is removed and replaced Mismatch excision repair o Mismatches that occur during replication are recognized, nucleotides are excised and replaced Nucleotide excision repair o Damages caused by UV radiation are repaired Double-strand break repair by end joining o Repaired by enzymes that catalyze the rejoining of broken helices or by homologous recombination Cancers and Hereditary Diseases Associated with DNA-Repair Defects Carcinogens are associated with increased risk of cancer, all are mutagens o Damage DNA which leads to the cell losing its capacity for controlled duplication and begins to undergo runaway replication Human predispositions to cancer, are genetic, is caused by an a genetic inability to repair DNA, because of missing proteins Hereditary xeroderma pigment sum – very sensitive skin to UV light, lack components necessary for DNA repair BRAC 1 and 2, are responsible for repair through recombination, which fixes double stranded breaks DNA polymerase introduces errors E. coli DNA polymerases introduces 1 error every 10,000 nucleotides.
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This note was uploaded on 10/23/2010 for the course BIOL BIOL 200 taught by Professor Bureau during the Fall '09 term at McGill.

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September 27 - Lecture 9 DNA Repair and Recombination Recombination takes place in eukaryotic organisms during meiosis where the genes are

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