Download下载.ppt

FBI uses 13 different DNA loci1:53,581,500,000,000,000,000 probability * Example of using STR Analysis in Forensics 49 murders in Seattle area 1982-1984 Bodies discarded in woods Task force investigated for years In 2001 DNA breakthrough led to further investigation including microscopic analysis of artifacts recovered with bodies Green paint spheres found on artifacts High end spray paint Linked bodies to each other Linked bodies to a common location / source - a single truck painting plant PCR-based STR analysis was used to convict the killer * Mitochondrial DNA in Forensics Mitochondria Organelles which are responsible for cellular respiration (ATP production) Have a double membrane, cristae (folds), a matrix, and their own DNA Mitochondria of the sperm cell do not enter the egg at fertilization Mitochondrial DNA (mtDNA) codes for proteins and enzymes used by the mitochondria Nuclear DNA also codes for enzymes used in the mitochondria * Nuclear DNA vs. Mitochondrial DNA Nuclear DNA found in nucleus of the cell double helix bounded by a nuclear envelope 2 sets of 23 chromosomes DNA packed into chromatin used with evidence such as saliva, semen, blood maternal and paternal can “discriminate between individuals of the same maternal lineage” Mitochondrial DNA found in mitochondria of the cell circular free of a nuclear envelope each mitochondria may have several copies of the single mtDNA molecule DNA is not packed into chromatin used with evidence such as hair, bones, teeth, and body fluid maternal only cannot “discriminate between individuals of the same maternal lineage” * Forensic mtDNA Analysis Steps to obtain a mtDNA sequence from a sample: Primary Visual Analysis Sample Preparation DNA extraction Polymerase Chain Reaction (PCR) Amplification Postamplification Quantification of the DNA Automated DNA Sequencing Data Analysis * Postamplification Purification and Quantification Purification is performed by using filtration devices that remove the excess reagents