BIO 315H Lecture Notes - Lecture 6: Dna Repair, Ap Site, Pyrimidine Dimer
Document Summary
Depurination purine gets removed and leaves an apurinic site; know that it removes a base. Deamination of c amine group is removed, can result in a point mutation. C or g changed to u (happens in dna, u is not supposed to be there, picked up and repaired) Basic excision repair - corrects abasic or apurinic sites. Particularly important for removing uracil (created by cytosine deamination) from dna. Normal g-c -> mutant t-a after replication (mispair) Tautomer = similar chemical forms that interconvert continually. Ex c doesn"t pair with g but pairs with a. X-rays break the sugar phosphate backbone of dna (deletion) Ultraviolet(uv) light causes adjacent thymines to form abnormal covalent bonds (thymine dimers) Protein scan and remove affected bases surrounding problem area. Trinucleotide repeats can expand or contract during replication. 20 human disease genes have unstable trinucleotide repeats. The central dogma information goes from dna to rna to protein. Transcription - reading dna to make rna transcript.
