ABC Forensic DNA study plan

Diagram the complete extraction pathway-substrate selection, lysis, purification, elution-and mark every step where DNA loss, inhibitor carryover, or contamination can enter.

Contrast organic, silica-membrane, and paramagnetic-bead chemistries on yield, inhibitor removal, and throughput, then defend a single choice for blood on fabric, bone, and a post-coital swab.

Trace differential extraction step by step, naming the reagent or physical treatment at each transfer and the reason it separates sperm from epithelial DNA.

Convert quantitation results into amplification input volumes and compute how dilution, concentration, or reduced input shifts the probability of allele drop-out.

Assemble a multiplex PCR master mix by component role-buffer, Mg2+, dNTPs, primers, polymerase, template-and predict the effect of doubling or halving each concentration.

Diagnose inhibition signatures (peak imbalance, locus drop-out, raised baseline, allelic ladder distortion) and prescribe one remediation step for each signature.

Explain how stochastic sampling at low template produces heterozygote imbalance and drop-out, and state the input level at which you would flag a sample for re-extraction.

Map a multiplex's dye channels, locus size ranges, and overlap zones, and identify which loci are most vulnerable to pull-up and dye-blob interference.

Annotate STR locus structure (repeat unit, flanking region, strand orientation) and assign alleles using ISFG conventions, including microvariants and off-ladder designations.

Trace the electrokinetic injection-to-detection path-injection voltage and time, capillary, polymer, laser, detection optics-and relate each parameter to signal intensity and split-peak risk.

Distinguish stutter, pull-up, dye blob, incomplete 3-prime adenylation, and genuine tri-allelic patterns by their signature features, and set a data-supported threshold for each.

Size fragments against the internal lane standard and allelic ladder, and compute a base-pair size from migration data, showing the interpolation step.

Troubleshoot CE failures-failed injection, uniformly low signal, size-standard drop-out, current anomalies-by ordering probable causes from most to least likely and naming the check that confirms each.

Read a written three-person mixture data description and enumerate every component the peaks support, plus the components the data exclude.

State the criteria a single-source profile must meet for database upload, and identify which locus drop would disqualify it.

Draft the interpretation section of a case report for a two-person mixture at the level of detail a technical reviewer would demand.

Classify mixtures by component number, peak balance, and allele sharing, and justify each classification with the specific data points you would cite.

Compute random match probability, combined probability of inclusion, and likelihood ratios for stated genotype scenarios, showing every arithmetic step.

Explain the assumptions behind a likelihood ratio-relatedness, population substructure, allele frequency source, priors-and describe how a defense expert could attack each assumption.

Distinguish conclusions that are definitive exclusions from those that are inconclusive, and write one example of each in reporting language.

Estimate the major-to-minor ratio from written peak heights for a two-person mixture and identify which alleles must originate from the minor contributor.

Rank biological fluids and substrates by expected DNA yield and stability, and match each presumptive test result to the confirmatory test and body-fluid conclusion it supports.

Build a sampling plan for a multi-item mock case, ordering which items to test first and recording the reasoning that would hold up under cross-examination.

Explain how substrate interference-dyes, soil, humic substances-and environmental degradation alter downstream profile quality and interpretation limits.

Write a chain-of-custody and item-intake procedure from receipt through storage, naming every documentation checkpoint and the failure each one prevents.

Map the QA framework-validation, proficiency testing, reagent and ladder QC, equipment calibration, contamination monitoring, audits-to the specific audit finding or error each control is designed to catch.

Draft an SOP section for one workflow step that states scope, materials, procedure, acceptance criteria, and corrective action for an out-of-spec result.

Identify the legal and ethical obligations that attach to casework-discovery, admissibility standards, limits of expert testimony, confidentiality-and describe what each requires of the analyst in practice.

Deliver a spoken expert-testimony explanation of a likelihood ratio to a lay audience in under three minutes, then critique your own clarity and defensibility.

Complete a full-length timed mock exam spanning all five domains and sort every incorrect answer by domain and by error type (knowledge gap, misread, calculation slip).

Rewrite each missed concept as a flashcard and re-test those cards 24 hours later, logging the retention rate.

Assemble a one-page statistics formula sheet and a one-page artifact quick-reference index for final pre-exam review.