BIOL 330 Lecture Notes - Lecture 8: Xeroderma Pigmentosum, Pyrimidine Dimer, Dna Mismatch Repair
Document Summary
Photoreactivation- a repair mechanism that uses a white light dependent enzyme to split cyclobutane pyrimidine dimers formed by ultraviolet light. Excision repair- a type of repair system in which one strand of dna is directly excised and then replaced by resynthesis using the complementary strand as template. Base excision repair (ber)- a pathway of excision repair that recognizes damage to single bases, such as deamination or alkylation, and either repairs the base alone (short-patch repair) or replaces 2-10 nucleotides (long path repair) Nucleotide excision repair (ner)- an excision repair pathway that recognized bulky lesions in dna (such as uv-induced pyrimidine dimers: ner is divided into two major sub pathways. Transcription-coupled repair (tc_ner) which repairs damage in the transcribed strand of active genes. Global genome repair (gg-ner) which repairs damage anywhere in the. Deamination of unmethylated cytosine produces uracil which is probably why dna is the genetic material (its more stable: however, deamination of methyl cytosine produces thymine.
