AP BIOLOGY

Detailed explanation-1: -While a “proofreading” enzyme normally recognizes and corrects many of these errors, some mutations survive this process. Estimates of the frequency at which human DNA undergoes lasting, uncorrected errors range from 1 x 10-4 to 1 x 10-6 mutations per gamete for a given gene.

Detailed explanation-2: -Permanent changes in the DNA sequence, called mutations, can have serious consequences for cells and are repaired through mismatch repair, chemical reversal, excision repair, and double-stranded break repair.

Detailed explanation-3: -Most damage to DNA is repaired by removal of the damaged bases followed by resynthesis of the excised region. Some lesions in DNA, however, can be repaired by direct reversal of the damage, which may be a more efficient way of dealing with specific types of DNA damage that occur frequently.

Detailed explanation-4: -DNA Polymerases Lambda () and Mu () are members of the X-Family, and are primarily involved in DNA repair. Both polymerases function in repair of DNA double strand breaks (DSBs), a particularly toxic type of lesion that can result in chromosomal rearrangements or cell death if not corrected.