Just as impressive as the speed of __is its specificity.
· Only minute amounts of DNA need be present in the starting material, and this DNA can be in a partially degraded state, as long as a few molecules contain the complete target sequence.
· The key to this high specificity is the __, which hydrogen bond only to sequences at __ ends of the target segment. (For high specificity, the primers must be at least __ nucleotides long.)
· By the end of the __cycle, __ of the molecules are identical to the target segment, with both strands the appropriate length.
· With each successive cycle, the number of target segment molecules of the correct length doubles, soon greatly outnumbering all other DNA molecules in the reaction.