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Frame-shift mutations are often caused by which of the following changes to DNA. a. chemical modification b. insertion c. reversion d. transversion e. suppression How can the mismatch repair system of E. coli distinguish which one of two mis-paired bases to remove? a. DNA glycosylases b. altered DNA structure c. pattern of methylation d. 3′ rightarrow 5′ exonuclease activity e. AP endonucleases. Spontaneous mutations can arise after purine bases are hydrolyzed from the sugar. How can this be repaired before replication? a using the homologous chromosome b with the mismatch repair system c using AP endonucleases e using nucleotide excision repair What is the root cause of why a PCR reaction only amplifies a specific region of a genome? a. use of Taq DNA polymerase b. use of deoxynucleotides c. cycling between high and low temperatures d. the sequence of the DNA primers e. pH/ionic conditions in reaction. The recognition site for the enzyme DpnII is GATC; it cuts just before the G. Why doesn’t the enzyme cut the bacterium’s own DNA at that sequence? a it doesn’t exist in the bacterium’s genome b it is methylated in the bacterium’s genome c. the bacteria don’t express this protein d. because it produces “sticky ends”