DNA Evidence - PowerPoint PPT Presentation

dna evidence n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
DNA Evidence PowerPoint Presentation
Download Presentation
DNA Evidence

play fullscreen
1 / 41
DNA Evidence
583 Views
Download Presentation
badru
Download Presentation

DNA Evidence

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. DNA Evidence How can DNA be used to solve Crimes?

  2. Objective: Describe how DNA can be analyzed and used as evidence. Do Now: Why is DNA considered circumstantial evidence? In groups of 5 or less, work together on the DNA questions. Write all names and answers on loose-leaf paper. Hand in. Closure: At a crime scene, list at least 3 places investigators should look for DNA evidence.

  3. Objectives: Describe what DNA is and identify the different types of DNA Do Now: Where can DNA come from? Brainstorm all evidence that may have DNA

  4. Objectives: Describe what DNA is and identify the different types of DNA What is DNA? DNA contains genetic information. Found on chromosomes located in the nucleus of our cells** Individual Evidence

  5. Objectives: Describe how DNA can be analyzed and used as evidence. Explain the importance of CODIS in forensic science. CYTOSINE THYMINE GUANINE ADENINE • Made up of base pairs: (think of a bar code) • A – T • C – G • The order of the base pairs determines the genetic code

  6. Complimentary Base Pairing AGTACG TCATGC

  7. Objectives: Describe how DNA can be analyzed and used as evidence. Explain the importance of CODIS in forensic science. Human DNA • 50% of a person’s DNA comes from each parent • 23 pairs (46 chromosomes) in nucleus of most cells* • 1 chromosome in each pair is inherited from mother and other from the father • Every person has a different DNA sequence expect identical twins. **How can we distinguish between identical twins apart?

  8. Objectives: Describe the different types of DNA can be analyzed and used as evidence. Types of Human DNA • NUCLEAR DNA: found in chromosomes • Used for DNA Fingerprinting • Unique to individual • MITOCHONDRIAL DNA: Found in mitochondria • Inherited from mother • Not unique • Example: bone, hair shaft

  9. Objectives: Describe how DNA can be analyzed and used as evidence. Why use mDNA? More stable over time/conditions* Can get more DNA if sample is limited Can get DNA from a highly degraded source

  10. Objectives: Describe how DNA can be analyzed and used as evidence. How is DNA used? Identify a victim Link or exclude suspect to crime scene/evidence Link multiple crime scenes Establish Maternity/Paternity

  11. Objectives: Describe how DNA can be analyzed and used as evidence. What Factors Affect DNA evidence Heat, sunlight, moisture, bacteria, and mold (this was a major issue in the O.J. Simpson Case) Not all DNA evidence will result in a usable DNA profile. DNA testing cannot identify when the suspect was at the crime scene or for how long.

  12. Objectives: Describe how DNA can be analyzed and used as evidence. Explain the importance of CODIS in forensic science. What is CODIS? Electronic database of DNA profiles that can identify suspects. DNA profiles from individuals convicted of certain crimes, such as rape, murder, and child abuse, are entered into CODIS and help identify possible suspects when no prior suspect existed.

  13. Objectives: Describe how DNA can be analyzed and used as evidence. Explain the importance of CODIS in forensic science. Introduction to DNA Fingerprinting http://www.youtube.com/watch?v=RLpalVirlTk#t=322

  14. Watch the video and then answer the questions. Video Link: http://videos.howstuffworks.com/tlc/29325-understanding-using-genes-to-help-solve-crimes-video.htm 1. When did DNA start to be an important tool in forensics?A. 1880s B. 1960s C. 1980s 2. What type of evidence does the FBI consider its most powerful tool?A. Fingerprints B. Blood C. DNA 3. What program is used to match DNA samples to possible contributors?A. CODIS B. AFIS C. DNA Code 4. What is it called when the program makes a match?A. Hot Hit B. Cold Hit C. Dead Hit 5. How many criminals have been convicted based on this software?A. 300 B. 900 C. 1,500

  15. Objectives: Describe the role of DNA in the O.J. Simpson case Do Now: What are some factors that degrade (affect) DNA?

  16. The answers are … 1. When did DNA start to be an important tool in forensics?A. 1880s B. 1960s C. 1980s 2. What type of evidence does the FBI consider its most powerful tool?A. Fingerprints B. Blood C. DNA 3. What program is used to match DNA samples to possible contributors?A. CODIS B. AFIS C. DNA Code 4. What is it called when the program makes a match?A. Hot Hit B. Cold Hit C. Dead Hit 5. How many criminals have been convicted based on this software?A. 300 B. 900 C. 1,500

  17. Objectives: Describe the role of DNA in the O.J. Simpson case http://law2.umkc.edu/faculty/projects/ftrials/Simpson/Dna.htm Complete DNA and the O.J. Simpson case study Closure: The DNA found at the scene only shows OJ was present for the crime. What other evidence could they/did they find to try to link him as their major suspect?

  18. Objectives: Describe how a DNA fingerprint is performed Do Now: What is a DNA Fingerprint? The method of identification based on an individuals DNA:

  19. Objectives: Describe how a DNA fingerprint is performed 2 Main Types of DNA Testing • RFLP: * analyzes variable lengths of DNA cut by restriction enzymes. • requires large amounts of DNA and no degradation RFLP: Restriction Fragment Length Polymorphism.

  20. Objectives: Describe how a DNA fingerprint is performed Restriction enzymes: cut DNA at specific base sequences resulting in variable lengths of DNA

  21. Objectives: Describe how a DNA fingerprint is performed Gel Electrophoresis: Method of separating molecules of DNA within an electric field based on the size and charge of DNA fragments

  22. Objectives: Describe how a DNA fingerprint is performed http://www.dnalc.org/resources/animations/gelelectrophoresis.html More probes taken, the better the match probability will be. Denim blue jeans actually interfere with the restriction enzymes!

  23. Objectives: Describe how a DNA fingerprint is performed How are gel electrophoresis results analyzed?

  24. Objectives: Describe how a DNA fingerprint is performed DNA and Paternity

  25. Objectives: Describe how a DNA fingerprint is performed • Complete the following activities: • Who are the parents • Which man is the father • Closure: If everyone gave their DNA to CODIS every substantial crime could be run through the CODIS program to produce cold hits. This would solve more crimes faster. Would you agree to giving your DNA to the government to run a program like that?

  26. Objectives: Describe how a DNA fingerprint is performed Do Now: What does a restriction enzyme do?

  27. Objectives: Describe how a DNA fingerprint is performed 2nd Main type of DNA testing: PCR: (Polymerase Chain Reactions) specific sequences of DNA that have high variability (differences) are copied millions of times • Less DNA needed and can be partially degraded

  28. Objectives: Describe how a DNA fingerprint is performed Newest type of DNA testing: STR: Evaluates specific short repeating regions (loci) within nuclear DNA FBI uses 13 standard specific STR regions for CODIS

  29. Person A Forensic sample STR STR G-G-C-C-X-X-X-G-G-C-C-X-X.. G-G-G-C-C-X-X-G-G-C-C-X-X….. PCR amplify STR region C-C-X-X-G-G C-C-X-X-X-G-G well well Gel electrophoresis For 1 STR sequence at 1 locus

  30. Objectives: Describe how a DNA fingerprint is performed Complete STR profile

  31. Objectives: Describe how a DNA fingerprint is performed STR match probabilities are 1 in a quintillion (1x1018) or more

  32. Objectives: Describe how a DNA fingerprint is performed • Complete “The break in” activity and concepts of biotechnology reading. And hand in. • Closure: Name three different reasons why a DNA profile may be needed to identify a person.

  33. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime • Do Now: What is an advantage to PCR over RFLP?

  34. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime • Start the individual DNA Fingerprinting Lab and hand in. • Closure: If we only have 4 bases (AGCT) that our DNA is made up of, how can everyone's DNA be completely different? Hand in your closure/do now sheet.

  35. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime Do Now: Can any two people have the same DNA? Can any have the same mDNA? Finish the individual DNA Fingerprinting Lab and hand in. Closure: Do other animals have DNA?

  36. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime Do Now: There’s a copy of our entire DNA sequence in every cell of our body with one exception: red blood cells. But our sex cells only have ______ of our DNA. Finish the individual DNA Fingerprinting Lab and hand in. (20min)

  37. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime Complete the DNA profile review sheet. Hand it in. Closure: Besides determining suspects or paternity, what else can DNA be used for?

  38. Objectives: Describe how a DNA fingerprint is performed Do Now: Why does the DNA travel to the bottom of the gel electrophoresis chamber? Watch the video and take notes on your handout. This will be due tomorrow when we finish the video. Closure: What DNA did the suspect leave behind?

  39. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime Do Now: What are the base pairs I DNA and how do they match up? Start the group DNA profile lab and hand in. Closure: One chromosome can have as little as 50 million base pairs or as much as 250 million base pairs. How many chromosomes do we have?

  40. Objectives: Construct a gel electrophoresis simulation and determine who committed the crime Do Now: What does the gel electrophoresis do? Complete the group DNA profile lab and hand in. Closure: Check your grades. Write down what you are missing.