Forensic DNA Exam – STR Genotyping, Capillary Electrophoresis & Data Interpretation Verified Questions Complete with A+ Graded Rationales Latest Updated 2026

Forensic DNA Exam – STR Genotyping, Capillary Electrophoresis & Data Interpretation Verified Questions Complete with A+ Graded Rationales Latest Updated 2026 What are the 3 requirements for successful STR typing? 1. spectral resolution 2. spatial resolution 3. DNA sizing and precision Spectral resolution separate fluorescent dye colors so PCR products with different dyes can be resolved Spatial resolution separate PCR fragments that differ in size by a single nucleotide DNA sizing precision samples can be related to internal size standards and allelic ladders for calibration purposes Which 3 factors affect genotyping results? 1. matrix file 2. internal lane standard 3. allelic ladder Matrix file allows for proper color separation based on matrix standards Internal lane standard (ILS) allows for proper sizing of DNA fragments Allelic ladder every allele in the loci which allows alleles to be resolved from one another Electropherogram peaks are recorded in what domain? time (min) GeneScan software used for fragment analysis (spectrally resolve dye colors, label peaks according to thresholds, and size fragments) GenoTyper software used for genotyping (assign alleles by comparing sizes of peaks to allelic ladder) GeneMapper ID software with combined fragment analysis and genotyping Manual intervention in STR genotyping determination two independent reads of data (technical review by one analyst and then diff analyst reviews data) Analytical threshold RFU level that defines a true allele (peaks below AT cannot be used for inclusion or exclusion purposes) and can be used for exclusions ONLY Interpretation/Stochastic Threshold RFU level where peak is considered reliable and can be used for inclusions (and exclusions) and has a low probability of allele drop out Inclusion/failure to exclude/cannot exclude same genotype and no unexplained differences exist between samples What are the 3 events for a match? 1. the suspect deposited the sample 2. the suspect did not deposit the sample but has the profile by chance (adventitious match) 3. the suspect did not provide the sample and the matching result is a false positive due to lab error Exclusion genotype comparisons show differences that can only be explained as originating from 2 different sources How many mismatches in forensic casework lead to exclusions? 1 How many mismatches in paternity testing lead to exclusions? 2, gives possibility for mutation Inconclusive data does not support a conclusion either way or analysts disagree with findings What are t