The primary probe consists of two functionally different regions: a 5'-flap sequence and a 3' target-specific region (TSR). The sequence of the 5'-flap varies in length (typically 1-15 nucleotides) and, because it is indepen dent of the target, can consist of any sequence. The 3' base of the Invader oligo overlaps with the TSR of the primary probe at a base referred to as ''position 1,'' creating a substrate for the Cleavase enzyme. The specificity of the Cleavase enzymes requires that position 1 of the primary probe be complementary to the target for cleavage to occur, providing the ability to discriminate single-base changes. The generation of the proper enzyme substrate is dependent on association between the primary probe, Invader oligo, and target. A noncomplementary base in the target at position 1 results in the formation of a nicked structure, rather than an invasive structure, because position 1 of the primary probe effectively becomes part of the flap. The nicked structure is not a substrate for the Cleavase enzyme, and thus the noncomplementary primary probe does not get cleaved. Discrimination relies on enzymatic recognition of the properly assembled structure in addition to the sequence specificity of oligonucleotides to the target sequence.
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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.