What is the genotype frequency of the DNA Evidence for CSF1PO? Hint: Notice that the evidence have two different alleles in their genotype, a 5 and a 6, so you will need to use the genotype frequency calculation for heterozygous genotypes. Also, recall that in the previous two questions, you calculated the allele frequencies for alleles 5 and 6 separately, so you are ready to incorporate them into the heterozygous genotype frequency formula. Round your answer accurately to the 3rd decimal place.

In Part 1 of this lesson, students learn the basics of DNA profiling, including the structure and inheritance of STRs.

In Part 2, students learn how DNA profiles are compiled with STRs that are typically used in forensic

investigations. In Part 3, they work through a case study involving a robbery and build a DNA profile that can be

compared to one constructed from a DNA sample left by a suspect at the scene of the crime. Throughout, analysis

questions walk students through calculations on allele frequency and probability (using real data from national

databases), providing opportunities for formative assessments on students’ understanding of DNA fingerprinting

applications.

This lesson can be used on its own or followed by the accompanying case studies in which students apply what

they have learned to solve four cases: 1) twins switched at birth, 2) revisiting evidence from a crime for which the

accused was sentenced to life in prison, 3) identifying a missing person, and 4) identifying victims of an

earthquake.

KEY CONCEPTS AND LEARNING OBJECTIVES

A. Regions of highly variable, noncoding, nonregulatory DNA known as short tandem repeats (STRs) are used

to build genetic profiles, which can be used in forensic investigations.

B. STRs are found across the genome. The more STR loci used to build a genetic profile, the more confident

Explanation: Investigator should be more proactive