Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Zinc finger nuclease wikipedia , lookup
DNA repair protein XRCC4 wikipedia , lookup
Homologous recombination wikipedia , lookup
DNA sequencing wikipedia , lookup
DNA replication wikipedia , lookup
DNA nanotechnology wikipedia , lookup
DNA profiling wikipedia , lookup
DNA polymerase wikipedia , lookup
Helitron (biology) wikipedia , lookup
DNA Forensic Identification Ashley Kowaleski I400 Objectives What is forensic science? How and when did forensics begin? When was DNA identification discovered? What is DNA identification used to determine? What exactly are forensic scientist looking for? What is the process does DNA identification involve? How are criminals processed? What is the outlook for the future? Forensic Science Process of gathering and examining evidence of a crime First practiced forensic medicine in 1958 Italy Application of medical knowledge to legal questions Unique Identifiers Fingerprints When a persons hand touched a surface, it left a barely visible mark Each person’s fingerprint is a unique identifier of that person, no two people’s are alike DNA Genetic material that is found in DNA is also a unique identifier Not until1985 when DNA became part of forensic science DNA (deoxyribonucleic acid) Nucleic acid that carries the genetic information Double helix 2 long chains of nucleotides twisted and joined by hydrogen bonds Can be found in white blood cells Polymorphic: vary in shape from person to person DNA Identification Uses Investigations of criminal cases involving victims Assault Kidnapping Robbery Rape Murder Catastrophe victims Paternity/family relationships Identify endangered and protected species Detect bacteria/organisms that may pollute the air, water, food, and soil Match organ donors with recipients Determine pedigree for seed/livestock breeds Authenticate consumables such as caviar and wine Short Tandem Repeats (STR) STR regions are nucleotides along the backbone of a chromosome 13 markers used in forensic science Classified into groups depending on the size of the repeat regions Mini satellites Micro satellites The chance that any two peoples DNA fingerprint for a particular set of regions is exceptionally small 1/10th of a single % of DNA, about 3 million bp, differ from one person to the next The Process Isolation Quantifying Polymerase Chain Reaction (PCR) Short Tandem Repeat-Polymerase Chain Reaction (STR-PCR) Interpretation Database Isolation Scientist extract DNA from the nucleus of cells in tissue Quality of tissue DNA samples degrades as body decomposes 1-4 hours Quantifying Tests are run to determine the amount of DNA recovered Targeted amount 1 nanogram (billionth of a gram) If inadequate quantity, isolation must be repeated 1-2 hours Polymerase Chain Reaction (PCR) One of the most popular and widely used techniques in molecular biology Reproduces millions of exact copies of specific fragments of DNA Enables even highly degraded samples to be analyzed 3 hours Polymerase Chain Reaction (PCR) Polymerase Chain Reaction (PCR) Based on polymerase enzyme Break apart double helix, two single strands Rebuild two strands into two complete helixes DNA deposited into polymerases and nucleotides Repeated rapidly, doubling amount of DNA STR-PCR Mainly same process Focus solely on STR regions Since these repeat regions are usually bounded by specific restriction enzyme sites, it is possible to cut out the segment of the chromosome Capillary Electrophoresis (CE) Early 1990’s Automated analytical technique Generally used for separating ions, which move at different speeds when the voltage is applied depending on their size and charge. The solutes are seen as peaks as they pass through the detector Area of each peak is proportional to their concentration Produces a chart mapping a person’s exact genetic makeup This is the information used to compare suspects to a crime http://chemi.muni.cz/~analytika/ce/ce-animation.gif Capillary Electrophoresis Interpretation A DNA scientist reviews the DNA profile produced through the capillary electrophoresis to determine if there is a match STR markers are examined (2-5 bp) 1-3 are not enough to determine is the sample came from the suspect 4-5, beyond a reasonable doubt 5 very rare National DNA Databank: CODIS The COmbined DNA Index System Blends computer and DNA technologies into a tool for fighting crime 2 indexes Convicted Offender Index DNA profiles of individuals convicted of criminal crimes Forensic Index DNA profiles developed from crime scene evidence All profiles stored in CODIS are generated using STR analysis The Future March 2004: President Bush proposed $1 billion in funding over the next 5 years Reduce DNA testing backlog Build crime lab capacity Stimulate research and development Support training Protect the innocent Identify missing persons