Which description best defines an STR DNA profile?

Which description best defines an STR DNA profile?

• A. It uses Short Tandem Repeats across multiple loci
• B. It uses a single locus
• C. It relies on appearance of the suspect
• D. It measures blood type

Answer: (A)

STR DNA profiling analyzes Short Tandem Repeats at multiple loci across the genome. Each STR locus has a repetitive DNA sequence that varies in number of repeats between individuals, and examining many of these loci together creates a unique pattern for almost every person (excluding identical twins). This multi-locus approach provides the high level of discrimination needed in forensics because the chance of two unrelated people sharing the same combination of repeats across all those loci is extremely small. Using a single locus wouldn’t give enough specificity, since one locus can be shared by more than one person. Appearance describes physical traits, not the genetic sequences analyzed in STR profiling. Blood type is a separate genetic trait and not part of the STR pattern used to identify individuals.

STR DNA profiling analyzes Short Tandem Repeats at multiple loci across the genome. Each STR locus has a repetitive DNA sequence that varies in number of repeats between individuals, and examining many of these loci together creates a unique pattern for almost every person (excluding identical twins). This multi-locus approach provides the high level of discrimination needed in forensics because the chance of two unrelated people sharing the same combination of repeats across all those loci is extremely small.

Using a single locus wouldn’t give enough specificity, since one locus can be shared by more than one person. Appearance describes physical traits, not the genetic sequences analyzed in STR profiling. Blood type is a separate genetic trait and not part of the STR pattern used to identify individuals.