LECTURE: DNA MUTATIONS AND REPAIR
LECTURE: DNA MUTATIONS AND REPAIR KIRSTIN BROWN
Lecture: DNA MUTATIONS AND REPAIR Outline: 1. Types of mutations 2. Repair mechanisms 3. Telomerase
Types of mutations DNA polymerase sometimes makes mistakes o Point mutations: one base pair is substituted for another, incorrect base pair
o Insertion mutations: one or more base pairs are added where they do not belong o Deletion mutations: one or more base pairs are removed from the new strand Normal Point mutation Insertion Deletion
Types of mutations DNA polymerase III has exonuclease activity o Exonuclease activity: breaks phosphodiester bonds to remove incorrect base pair and to correct mistakes
Types of mutations Sometimes, DNA polymerase misses a mistake o DNA mismatch repair: repair enzymes recognize incorrect geometry
Telomeres DNA strands are shortened after each replication o DNA polymerase III can’t replicate the ends of the lagging strand
Telomeres DNA strands are shortened after each replication o Telomerase extends the ends to prevent shortening
Lecture: DNA MUTATIONS AND REPAIR Outline: 1. Types of mutations 2. Repair mechanisms 3. Telomerase
Types of mutations DNA polymerase sometimes makes mistakes o Point mutations: one base pair is substituted for another, incorrect base pair
o Insertion mutations: one or more base pairs are added where they do not belong o Deletion mutations: one or more base pairs are removed from the new strand Normal Point mutation Insertion Deletion
Types of mutations DNA polymerase III has exonuclease activity o Exonuclease activity: breaks phosphodiester bonds to remove incorrect base pair and to correct mistakes
Types of mutations Sometimes, DNA polymerase misses a mistake o DNA mismatch repair: repair enzymes recognize incorrect geometry
Telomeres DNA strands are shortened after each replication o DNA polymerase III can’t replicate the ends of the lagging strand
Telomeres DNA strands are shortened after each replication o Telomerase extends the ends to prevent shortening
