Biology 1001A Lecture Notes - Lecture 9: Chromosome, Pyrimidine Dimer, Thyroid
Document Summary
Clicker question: when does crossing over occur between homologous chromosomes. Repairing double stranded breaks create copy number variations in a genome. Physical mutations caused by radiation, by environmental factors. Clicker question: why is the wrong tautomeric form of thymine not removed by mismatch repair. Mismatch pair doesn"t break h bonds, it breaks the backbone -> a is wrong. Dna polymerase is not part of mismatch repair, dna polymerase is used for proofreading -> c is wrong. If thymine switched to it"s other tautomer it would still be matched with a g -> d is wrong. Therefore the answer is b since the pairings doesn"t distort the helix cannot be detected by mismatch repair, cannot be fixed. Some mutagens are tautomerically unstable base analogues thymine and uracil the difference is only the methyl group. 5-bromouracil is a base analogue (looks like thymine) have time telling the difference from 5- bromouracil and thymine.
