Name ________________________________________ Date ________________ Forensics of DNA Go online to http://www.dna.gov/basics/analysishistory and complete the following worksheet. HISTORY OF DNA ANALYSIS 1. _______________________________or DNA typing (profiling) as it is now known, was first described in ______ by an English geneticist named _________________________. 2. Dr. Jeffreys found that certain regions of DNA contained ________________________________ that were repeated over and over again next to each other. He also discovered that the number of repeated sections present in a sample could differ from individual to individual. By developing a technique to examine the length variation of these DNA repeat sequences, Dr. Jeffreys created the ability to perform ____________________________. 3. These DNA repeat regions became known as __________, which stands for ____________________________________. The technique used by Dr. Jeffreys to examine the VNTRs was called _________________________________________ (RFLP) because it involved the use of a ____________________________to cut the regions of DNA surrounding the VNTRs. 4. Today over _________ public forensic laboratories and several dozen private paternity testing laboratories conduct ________________________ of DNA test annually in the United States. BIOLOGY OF DNA 1. DNA is the abbreviation for _________________________________, which is the genetic material present in the cells of all living organisms. 2. A person's DNA is the same in every ___________ (___________________). The DNA in a person's blood is the same as the DNA in their ___________________, _________________, and ________________________. 3. DNA is comprised of four building blocks called _______________. The building blocks are: _________________, ___________________, ___________________, _____________________. These are commonly referred to as ___, ___, ___, ____. 4. DNA is contained in________________________________________________ _____________________________________________________________________. GATHERING DNA EVIDENCE 1 Name ________________________________________ 1. ____________________________, ____________________________. which Date ________________ contains DNA, is a type of 2. All biological evidence found at crime scenes can be subjected to ______________________. IDENTIFYING DNA EVIDENCE 1. List where and what could be collected from a piece of physical evidence that may lead to DNA evidence: a. b. c. d. e. hat __________________________, envelope _____________________, pillow _______________________, fingernail ___________________, soda can _____________________, ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ CRIME SCENE INTEGRITY 1. While documenting evidence at the crime scene, include descriptions of whether evidence was found ________ or ________. An example of this documentation would include __________________________. 2. The risk of _____________________________ of any crime scene can be reduced by limiting _________________________________. Because DNA evidence is ___________________________than other types of evidence, law enforcement personnel should be especially aware of their actions at the scene to prevent inadvertent _________________________________________________. CHAIN OF CUSTODY 1. The _______________________________ of evidence is a record of individuals who have had ________________________ of the evidence. ______________________________ is critical to maintaining the integrity of the chain of custody. 2. Because extremely small samples of DNA can be used as evidence, greater attention to contamination issues is necessary when _______________________, ________________________, and _________________________ DNA evidence. DNA evidence can be contaminated when DNA from another source gets mixed with DNA relevant to the case. TRANSPORTATION AND STORAGE 1. As with any evidence, the officer should ensure that the ______________________________ is maintained. In addition, they should be aware that __________________ and _______________________________may degrade DNA, and avoid storing 2 Name ________________________________________ Date ________________ evidence in places that may get hot, such as the trunk of the police car. To best preserve DNA evidence, store in a _______________________________. 2. Any probative biological sample that has been stored _______ or ______________, regardless of age, may be considered for DNA analysis. ____________________________ from blood and semen stains more than 20 years old has been analyzed successfully using _________________________________ (PCR). 3. Samples that have been stored _______for an _______________________________ should be considered for testing only using ________ and may be unsuitable for DNA analysis. ___________________________________ has been performed on very old bones, teeth, and hair samples. ANALYZING DNA EVIDENCE 1. Several basic steps are performed during DNA testing regardless of the type of test being done. The general procedure includes: 1) ____________________________________________________________________ __________;2) ___________________________________________________; 3)_________________________________________; and 4) _______________ ___________________________________________________________________ 2. Each additional test at a previously ______________________ (location or site) in the DNA provides another opportunity for the result of "_________________________" if the known individual being used for comparison is not the source of the DNA from an evidence sample of unknown origin. 3. When a sufficient number of tests have been performed in which an individual cannot be __________________ as the ______________ of the DNA by any of the tests, a point is reached at which the tests have excluded virtually the world's _____________________ and the unique identification of that individual as the source of the DNA has been ________________. 4. Possible results from DNA testing include: 1) _______________; 2) _________________; and 3) ________________. 5. _________________________ requires a biological sample about the size of a quarter, but _____ can be used to reproduce millions of copies of the DNA contained in a few skin cells. 6. ____________________________ (_____) technology is a forensic analysis that evaluates specific regions (________) that are found on nuclear DNA. The variable (________________) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA ___________ and another. 3 Name ________________________________________ Date ________________ 7. The Federal Bureau of Investigation (FBI) has chosen ____ specific STR loci to serve as the standard for __________. 8. Advancements in _______________________________ may eventually eliminate the need for laboratories to extract and separate semen and vaginal cells (for example, from a vaginal swab of a rape kit) prior to analysis. 9. _________________________ (mtDNA) analysis allows laboratories to develop DNA profiles from evidence that suitable for RFLP or STR analysis. While RFLP and PCR analyze DNA extracted from the nucleus of a cell, mtDNA analyzes DNA found in a different part of the ______________________. forensic may not be techniques technology cell, the 10) Old remains and evidence lacking _______________________--such as hair shafts, bones, and teeth--that are unable to be STR and RFLP tested, may yield results if __________________ is performed. For this reason, mtDNA testing can be very valuable to the investigation of an _________________________. 4