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Chapter 10

DNA profiling has revolutionized biological identification and forensic science.  The principles we covered in the last chapter such as electrophoresis, genetic marker systems and combining probabilities used in a more expansive and specific way. The material covered in this chapter is also more complex than we have tackled so far.  

We’ll begin with a brief discussion of early DNA methods and move quickly into current methods and practices. Topics include short tandem repeats (STRs), amplification of DNA using PCR, and instrumental analysis via capillary electrophoresis.  You will the basics of how to interpret a DNA analysis report, and how frequency databases are used to generate probabilistic metrics regarding the output.    

10.1 Describe the sources and basic structure of DNA 

10.2 Differentiate between genes, loci, VNTRs, and STRs 

10.3 Describe the basics of PCR amplification of STRs including the use and function of labeled primers 

10.4 Recognize key features of an electropherogram and their functions 

10.5 Describe the steps of a DNA profiling analysis 

10.6 Describe how DNA results are interpreted 

10.7 Recognize the application of combined probabilities and frequency databases in DNA profiling. 

Question 1

Match the step to the appropriate description related to PCR

Annealing
Primer
Amplicon
Thermal cycler
Denaturization
Copy of the original DNA
Unzipping of the DNA strand
Specialized molecular probes that locate a specific DNA locus
Binding of primer to target DNA
Instrument that controls temperatures
Question 2

Terms associated with DNA analysis 

Dye channel
Capillary electrophoresis
Genotype
Internal size standard
Electropherogram
Peak height threshold
Allelic ladder
Portion of the DNA fragments that have the same fluorescent dye
Instrument used to generate a DNA profile
The smallest size peak considered to be a genuine signal from a DNA sample
A control standard that contains the common alleles for a given locus
Number of repeats of an STR at a given locus
Output of a CE instrument
A control sample of known DNA fragment sizes
Question 3

Assume a Q vs K comparison of single source DNA profile involves  three lociHow would you interpret the following results? A .. indicates no results 

Locus 1: 6,9 Locus 2: 7,7 Locus 3: 4,5 Locus 1: 6,9 Locus 2: 7,7 Locus 3: 4,5
Locus 1: 7,3 Locus 2: 3,2 Locus 3: 4,9 Locus 1: 7,3 Locus 2: 2,1 Locus 3: 4,9
Locus 1: 7,3 Locus 2: 3,2 Locus 3: 4,9 Locus 1: 7,8 Locus 2: 2,1 Locus 3: 4,9
Locus 1: 14,19 Locus 2: 7,9 Locus 3: 4,9 Locus 1: 14,.. Locus 2: ..,7 Locus 3: 4,..
Indeterminate
Exclusion
Inclusion
Exclusion

The hot spot activity will be added shortly.