Biochemistry 2280A Lecture Notes - Lecture 21: Dna Mismatch Repair, Lig4, Dna Ligase
Document Summary
Describe and differentiate between the different kinds of commonly observed dna damage. Predict which repair mechanism will be used to repair a particular instance of dna damage. Predict the consequences of dna damage that is not repaired before the next round of replication. Describe the role of translesion dna polymerases as they relate to dna damage. Any unintended physical or chemical change in dna or its sequence. Cells assume that the beginning sequence is the preferred sequence o o. If anything unusual happens to the dna, the cell is going to try to get back to the sequence that it had originally. Dna molecules are huge and are prone to damage. To try and preserve nucleotide sequence, cells have developed mechanisms for repairing dna damage. Copying mistakes: dna polymerase makes an error about 1 in 107 nucleotides. Depurination: loss of entire guanine or adenine base. Result: blocks dna replication (can be overcome by error-prone translesion dna polymerases) o.