Accurate genotyping requires stringent allelic discrimination. ARMS-PCR relies on 3'-end primer mismatching to achieve a high degree of allelic specificity. As shown in Fig. 1, the original two-tube incarnation of ARMS-PCR utilizes five primers—two of these are allele-specific and complementary to the polymorphic site at their 3' terminus, while a common companion primer serves to yield an allele-specific amplification product. Because Taq DNA polymerase lacks 3'! 5' exonuclease activity,1-7-1 allelic specificity is conferred by its inability to efficiently extend 3' end-mismatched primers. Because most known SNPs are biallelic, two reactions (each containing either one of the allele-specific primers) are required for definitive genotype assignment. An additional pair of irrelevant, fully matched primers, yielding an amplicon of different size serves as internal control to flag false-negative reactions (i.e., those resulting from amplification failure).
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.