DNA Analysis & Interpretation Flashcards
7 cards from real CFC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 DNA Analysis & Interpretation flashcards as text
A forensic analyst obtains a DNA profile from a degraded sample with only 8 of 20 CODIS loci amplified. What is the most appropriate course of action?
Answer: Compare the partial profile and note the reduced statistical weight
Partial profiles can be compared, but the statistical weight is reduced and limitations must be clearly communicated in the report.
Which phenomenon occurs when a smaller DNA allele is preferentially amplified over a larger allele during PCR, leading to apparent homozygosity?
Answer: Allelic dropout
Allelic dropout occurs when one allele in a heterozygous sample fails to amplify, often due to low template DNA or degradation.
In forensic DNA analysis, what does the term 'mixture ratio' refer to?
Answer: The relative proportion of DNA contributed by each individual in a mixed sample
Mixture ratio describes the proportional contribution of each individual's DNA in a mixed sample, important for deconvolution.
A forensic examiner observes a peak in a capillary electropherogram that is exactly one repeat unit smaller than a true allele. This artifact is called:
Answer: Stutter
Stutter artifacts are minor peaks one repeat unit smaller (or occasionally larger) than the true allele, caused by strand slippage during PCR.
When conducting Y-STR analysis on a sexual assault evidence sample, what is a key limitation forensic examiners must acknowledge?
Answer: Y-STRs cannot distinguish between male relatives sharing the same patriline
Y-STRs are identical among all paternally related males, so a match cannot exclude a brother, father, or other male paternal relatives.
What statistical measure is used to express the probability that two unrelated individuals share the same DNA profile in a given population?
Answer: Random match probability
Random match probability (RMP) estimates the chance that a randomly selected unrelated person in the population would have the same DNA profile.
A forensic analyst identifies three contributors in a DNA mixture. Which analytical approach is specifically designed for complex mixture interpretation?
Answer: Probabilistic genotyping software
Probabilistic genotyping software uses statistical models to evaluate contributor genotype combinations and compute likelihood ratios for complex mixtures.