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Forensic Sciences and DNA Fingerprinting

LECTURE 22:. Forensic Sciences and DNA Fingerprinting . Biotechnology; 3 Credit hours Atta- ur - Rahman School of Applied Biosciences (ASAB) National University of Sciences and Technology (NUST). Forensic Science. Forensic biology is the application of biology to law enforcement

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Forensic Sciences and DNA Fingerprinting

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  1. LECTURE 22: Forensic Sciences and DNA Fingerprinting Biotechnology; 3 Credit hours Atta-ur-Rahman School of Applied Biosciences (ASAB) National University of Sciences and Technology (NUST)

  2. Forensic Science • Forensic biology is the application of biology to law enforcement • The analysis of the biological or genetic properties of evidence for identification • It is used to establish identity in criminal investigation, in case of disputed paternity, or in historical or archaeological research

  3. The Genetic Basis of Identity • Fingerprints • Retinal Scan • Blood Typing • DNA Fingerprinting

  4. 1- Fingerprints • Finger prints are the classic example of a phenotype used in law enforcement • They are due to the variation in the pattern of dermal ridges, small skin elevation on your fingers

  5. Fingerprints • Fingerprints pattern depends on more than one gene • They are multigenic • This create huge genetic diversity underlying this phenotype • One could expect fingerprints of twins identical, but they are not • Minor variation happens because of environmental factors • This science is being used for identification by late 1800

  6. 2- Retinal Scan • Retinal scan provide a more high tech form of unique identification • It take advantage of unique pattern of blood vessels on the retina on the back side of eye

  7. Retinal Scan • Scanning typically take about a minute • Several scans are required • Infrared light is used for this job, because blood vessel on the retina absorb this better than the surrounding tissue • A computer algorithm is used to convert this scan into digital data • There are about 10 fold more information on retinal scan than in fingerprints

  8. Applications • Application in high security system • CIA, FBI, NASA and prison system • Now it is being employed on animal identification • Fingerprinting in many security system and also in law enforcement system (crime secene)

  9. 3- Blood Typing • Blood typing has been used in the courtroom for more than 50 years • Other body fluids i.e. Sweat, tears, urine, saliva and semen also have cells with surface proteins that can be analyzed • RBC contain many proteins and lipids for the identification

  10. Blood Typing • Galactosetransferase • N-acetylgalactosaminetransferase

  11. Blood Typing

  12. Inheritance of ABO blood system

  13. 4- What is a DNA fingerprint? • DNA profiling (also called DNA testing, DNA typing, or genetic fingerprinting) is a technique employed by forensic scientists to assist in the identification of individuals by their respective DNA profiles. • DNA profiles are code sets of numbers that reflect a person's DNA makeup, which can also be used as the person's identifier. • It is used for parental testing and crime investigation.

  14. DNA fingerprint Profiling Analysis • RFLP Analysis • PCR Analysis • STR Analysis • AmpFLP Analysis • Mitochondrial DNA Analysis • Y-chromosome DNA Analysis

  15. a. RFLP Analysis

  16. b. PCR Analysis

  17. c. STR Analysis

  18. PCR Analysis

  19. Paternity Testing PCR amplification, then DNA fingerprinting

  20. Mother’s STRs Offspring STRs STRs of suspected Father - Is the suspect the father?

  21. d. Genealogies by Mitochondrial & Y-chromosome DNA Analysis • Genealogy is the study of families and the tracing of their lineages and history • Mitochondrial DNA is maternally inherited and often used to specifically trace maternal ancestry • Y chromosome can be used to trace male ancestry

  22. Genealogies by Mitochondrial & Y-chromosome DNA Analysis • It is possible to submit personal samples of DNA for analysis to companies such as Oxford ancestor • Their matri-Line service allows persons of European decedent to trace their maternal ancestry back to one of seven ancestral females

  23. Genealogies by Mitochondrial & Y-chromosome DNA Analysis • Y-chromosome follows a paternal pattern of inheritance. • The Y-chromosome contain many STR sequence in non-coding region. • Y linked STR loci are specific to Y-chromosome • They find useful application in forensic analysisin case of sexual assault.

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