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Figure 2.8 The original data for the DNA profile given in Table 2.2 and Problem box 2.1 obtained by capillary electrophoresis. The PCR oligonucleotide primers used to amplify each locus are labeled with a molecule that emits blue, green, or yellow light when exposed to laser light. Thus, the DNA fragments for each locus are identified by their label color as well as their size range in base pairs. (a) A simulation of the DNA profile as it would appear on an electrophoretic gel (+ indicates the anode side). Blue, green, and yellow label the 10 DNA-profiling loci, shown here in grayscale. Other DNA fragments are size standards (originally in red) with a known molecular weight used to estimate the size in base pairs of the other DNA fragments in the profile. (b) The DNA profile for all loci and the size-standard DNA fragments as a graph of color signal intensity by size of DNA fragment in base pairs. (c) A simpler view of trace data for each label color independently with the individual loci labeled above the trace peaks. A few shorter peaks are visible in the yellow, green, and blue traces of (c) that are not labeled as loci. These artifacts, called pull-up peaks, are caused by intense signal from a locus labeled with another color (e.g. the yellow and blue peaks in the location of the green-labeled amelogenin locus). A full-color version of this figure is available on the textbook website.

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