Genetics Unit 3 IP - DNA Profiling 1. Explain the use(s) of DNA profiling, and describe at least 1 benefit and 1 drawback. DNA profiling is a molecular biology technique that can provide helpfull information in many areas such as parentage testing and criminal investigation. Unless there is a reason to do DNA profiling such as knowing who are your parents DNA profiling is not very useful. Today there are many other kinds of DNA analysis, i.e. diseases predisposition, ancestry ecc ecc Benefit The process can be used to identify potential suspects and link suspects to a crime, proving they were at a certain place. DNA profiling also enhances the criminal system's accuracy. Drawback It is a complicated and tedious process, at times giving results that are hard to interpret. 2. Describe the steps involved in creating a DNA profile. Extraction DNA is located within the nucleus of cells throughout the body and the extraction step is responsible for breaking open the nucleus and releasing the DNA molecules into solution. During this step it is also possible to separate the DNA molecules from all other cellular material and any other debris that may be present in a particular biological sample. Some of these materials can be potential “inhibitors” to steps later on in the DNA testing procedure so it is important to try and isolate only the DNA molecules. Common inhibitors commonly found in forensic cases are hemoglobin and indigo dyes from denim. Two common methods of extraction used at the BCA are a manual PhenolChloroform (otherwise known as Organic Extraction) and through the use of a robotic system called the Maxwell® 16. Running samples on the Maxwell® 16 takes a minimum of two hours and samples extracted manually using the Phenol-Chloroform method takes a minimum of three hours. Quantitation One of the standards all DNA testing laboratories must meet is to ensure that the DNA recovered from an extraction is human rather than from another source such as bacteria. This is done through quantitation where the quality and quantity of DNA present in a sample is measured and assessed. Additionally, determining the amount of DNA in a sample is essential for success in the next step since most amplification systems require a narrow range of input DNA. This step is completed at the BCA through the use of a purchased Quantifiler DNA Human Quantification Kit and then running all samples on an instrument known as the ABI PRISM 7500 Sequence Detection System. This process takes approximately 30-60 minutes to set-up and then approximately two hours to run on the instrument. Amplification DNA amplification is accomplished through the use of a technique known as Polymerase Chain Reaction (PCR). PCR is a process in which millions of copies of a specific sequence of DNA can be made in a matter of only a few hours. This is important for forensic DNA samples since the DNA often found at crime scenes is limited in both quantity and quality. This molecular “xeroxing” process is completed by precise heating and cooling of the samples in a thermal cycling pattern for approximately 28 cycles. The amplification kit used by the BCA amplifies 15 different regions of DNA as well as a sex-determining marker. The BCA uses a purchased AmpFlSTR Identifiler kit and then the samples are run on an instrument known as the GeneAmp PCR System 9700. This process takes approximately 15-30 minutes to set-up and then approximately three hours to run on the thermalcycler instrument. Capillary Electrophoresis (CE) After the PCR reaction is completed it results in a large mixture of amplified DNA molecules which need to be separated in order to distinguish the various molecules from one another. This is accomplished through a process known as capillary electrophoresis. DNA molecules carry a negative charge and once an electric current is applied to the sample the molecules enter a very thin capillary filled with a gel-like polymer and migrate towards the positive anode at the other end of the capillary. The PCR products are then separated by size because the smaller DNA molecules will have an easier time migrating through the polymer than the larger DNA molecules. The data from this process is then collected on a computer attached to the CE instrument and then through the use of a software program a DNA profile is developed. The BCA uses an instrument called the ABI Prism® 3130 Genetic Analyzer which is capable of analyzing four samples at a time. Set-up for this step takes approximately 10 -15 minutes and each injection on the 3130 takes approximately 45 minutes. 3. Although DNA profiling services are attractive because they can reveal “your unique ethnic background, and match you with newfound relatives” (MyHeritage, 2021). Such data can also be used for criminal profiling, such as what happened in the case of the Golden State Killer. Describe at least 1 psychological, cultural, or social factor that can influence an individual's decision to have their DNA analyzed, knowing not only that the information may be useful but also that the results may not be private. 4. Getting a clean and clear DNA profile can be influenced by the source of the sample. Researchers have tested various approaches and developed different kits for extracting the DNA from a sample and generating a profile. The table below compares two such DNA kits. If you were an investigator, address the following using only the data that are shown: a. Which kit would you choose if all you had was a cigarette butt? Explain why. b. Would you choose the same kit if all you had was a coffee cup? Explain your rationale. c. If you only had DNA Kit 1, what sample source would be the best to work from (e.g., blood swab, saliva, or clothing)? Explain why. Comparison of Two DNA Kits for % Successful