Practice question

Short tandem repeats comprise tandem arrays of two to six base pair motifs where individual variation derives from different copy numbers of the repeat unit at a given locus. DNA polymerase slippage during replication expands or contracts repeat tracts, creating alleles differing in length but not in base composition or methylation pattern. Enzyme activity is unrelated to structural polymorphism. Consequently, genotyping relies on measuring fragment length variation through capillary electrophoresis, reflecting inherited differences in repeat number critical for forensics and paternity testing.