Dna fingerprinting


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Dna fingerprinting

  2. 2. DNA   Is a unique to every person but the same for the cell to cell within the same person. DNA cannot be altered* – Actually DNA can be altered in the lab, but you can’t change your own DNA
  3. 3. Two kinds of fingerprint   Conventional fingerprint DNA fingerprint – Becoming the primary method for identifying and distinguishing among individual human being
  4. 4. What is DNA Fingerprinting?  A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA
  5. 5. Who Invented it?  The process of DNA fingerprinting was invented by Alec Jeffreys at the University of Leicester in 1985.  He was knighted in 1994.
  6. 6. DNA Fingerprinting Basics Different individuals carry different alleles. Most alleles useful for DNA fingerprinting differ on the basis of the number of repetitive DNA sequences they contain.
  7. 7. DNA Fingerprinting Real World Applications          Crime scene Human relatedness Paternity Animal relatedness Anthropology studies Disease-causing organisms Food identification Human remains Monitoring transplants
  8. 8. Crime    Forensic science is the use of scientific knowledge in legal situations. The DNA profile of each individual is highly specific. The chances of two people having exactly the same DNA profile is 30,000 million to 1 (except for identical twins).
  9. 9. Biological materials used for DNA profiling       Blood Hair Saliva Semen Body tissue cells DNA samples have been obtained from vaginal cells transferred to the outside of a condom during sexual intercourse.
  10. 10. A DNA Fingerprint When many genes are analyzed, each with many different alleles, the chance that two patterns match by coincidence is vanishingly small. A DNA fingerprint used in a murder case. The defendant stated that the blood on his clothing was his. What are we looking at? How was it produced?
  11. 11. DNA Profiling can solve crimes    The pattern of the DNA profile is then compared with those of the victim and the suspect. If the profile matches the suspect it provides strong evidence that the suspect was present at the crime scene (NB:it does not prove they committed the crime). If the profile doesn’t match the suspect then that suspect may be eliminated from the enquiry.
  12. 12. Example    A violent murder occurred. The forensics team retrieved a blood sample from the crime scene. They prepared DNA profiles of the blood sample, the victim and a suspect as follows:
  13. 13. Was the suspect at the crime scene? Suspects Profile Blood sample from crime scene Victims profile
  14. 14. Famous Cases   Colin Pitchfork was the first criminal caught based on DNA fingerprinting evidence. He was arrested in 1986 for the rape and murder of two girls and was sentenced in 1988.
  15. 15. Altantuyaa Malaysian police found fragments of bone, later verified as hers, in forested land near the Subang Dam in Puncak Alam, Shah Alam. Police investigation of her remains revealed that she was shot twice before C-4 explosives were used on her remains, although there has been later suggestion that the C-4 explosives may have killed her. When her remains were found their identity could only be confirmed with DNA testing.
  16. 16. Solving Medical Problems DNA profiles can be used to determine whether a particular person is the parent of a child. A childs paternity (father) and maternity(mother) can be determined. This information can be used in • Paternity suits • Inheritance cases • Immigration cases
  17. 17. Example: A Paternity Test By comparing the DNA profile of a mother and her child it is possible to identify DNA fragments in the child which are absent from the mother and must therefore have been inherited from the biological father. 
  18. 18. Is this man the father of the child? Mother Child Man
  19. 19. Paternity Test   In general the child’s DNA must be a combination of Mary’s DNA and one of the men. Which man is the father? Answer: Larry
  20. 20. DNA fingerprinting is used for identification.  DNA fingerprinting depends on the probability of a match. – Many people have the same number of repeats in a certain region of DNA. – The probability that two people share identical numbers of repeats in several locations is very small. (mother) (child 1) (child 2) (father)
  21. 21. Famous cases  In 2002 Elizabeth Hurley used DNA profiling to prove that Steve Bing was the father of her child Damien
  22. 22. Food Identification
  23. 23. The detection of pork in processed food L 1 14 2 3 4 5 6 7 8 9 10 11 12 13 BseD1 restriction profile of cyt b PCR products amplifiedfrom meat and food samples. L: 100 bp DNA ladder; 1: chicken, 2: beef; 3: mutton; 4: pork; 5, 6, 7: beef burgers; 8, 9, 10: chicken burgers; 11, 12, 13: sausages; 14: pork cocktail
  24. 24. The End…..