BIL 250 Lecture Notes - Lecture 2: Depurination, Dna Replication, Hydroxyl Radical

• School: University of Miami
• Department: Biology
• Course: BIL 250
• Professor: karenalvarezdelfin

Document Summary

Spontaneous mutations arise from replication errors and base. During dna replication, dna polymerase occasionally inserts incorrect nucleotides. Dna polymerases can proofread and correct these errors with the 3"-5" exonuclease activity, but they may persist if not detected and corrected. These types of errors, due to mispairing, predominantly lead ot point mutations. If a template dna strand loops out and becomes displaced or if dna polymerase slips, small insertions, and deletions can occur. Insertions and deletions can lead to frameshift mutations or amino acid insertions and deletion in the gene product. Replication slippage can occur everywhere in the dna but is more common in tandem repeated sequences. Purines and pyrimidines can exist in tautomeric forms alternate chemical forms that differ in the chemical configuration of the molecule. Tautomeric shifts can change the bonding structure, allowing non- complementary base pairing. May lead to permanent base-pair changes and mutations. Transition mutation due to a tautormeric shift in adenine.