Tuesday November 8th, 2016 Announcements Agenda ? In class Exam covering Chapter 5 Fingerprints and Chapter 6 DNA Fingerprinting Next Tuesday It’s a “Match Worksheet” From Friday DUE ON THURSDAY NO SCHOOL FRIDAY Agenda ? “Times are tough but I’m tougher. I’ll be fine.” Happy National Cappuccino Day Fun Fact: Coconuts and Cows kill more people than sharks every year

Chapter 6: DNA Fingerprinting

History of DNA in Forensics Mid 1980’s DNA fingerprinting dramatically changed forensic science, ability of law enforcement to link perpetrators with crime scenes Early 1990’s US military began collecting and storing blood samples of soldiers 1994 DNA Identification Act National index of DNA identification records of persons convicted of crimes

History of DNA in Forensics 1998 National DNA Index System (NDIS) DNA profiles contributed by federal, state, and local participating forensic laboratories CODIS (Combined DNA Index System) Collects, analyzes and communicates criminal DNA information By 2014 CODIS had: 11.1 million offenders DNA profiles 1.9 million arrestee DNA profiles

The Function and Structure of DNA DNA (Deoxyribonucleic acid): contains genetic material of a cell Watson and Crick received the Nobel Prize for their work describing the structure of DNA DNA found in human cells makes up the human genome Chromosomes: cell structure that contains genetic information along strands of DNA

The Function and Structure of DNA Chromosomes Continued 46 chromosomes found in the human body Half of your DNA is inherited from your mother and the other half is inherited from your father 23 from your mom 23 from your dad Males have one X and one Y sex chromosomes (XY) Females have two X chromosomes (XX)

Chromosomes are composed of many DNA double helixes

22 homologous pairs of autosomes followed by the 2 sex chromosomes

Genes Each chromosome contains many genes Genes: DNA sequences that have instructions that determine our inherited characteristics or traits Blood type Hair type Eye color Dimples Right or left handed

Check for Understanding 1 Collects, analyzes and communicates criminal DNA information Makes up the human genome Total number of chromosomes found in the body The female sex chromosome The male sex chromosome DNA sequences that determine our inherited characteristics

DNA Identification Variations which exist in our DNA is found in our Noncoding DNA Dr. Alec Jeffreys developed a technique for isolating and analyzing the variations known as DNA Fingerprinting DNA Fingerprinting: known as DNA profiling; used in criminal and legal cases to determine identity or parentage Accurately predicts whether an individual can be linked to a crime scene or excluded Each individual’s DNA has a unique band pattern Forensic scientist focus on 2 types of repeating DNA; VNTR and STR

DNA Identification VNTR (variable numbers of tandem repeats) Used mostly for matching tissues and determining inheritance STR (short tandem repeat) Most useful for DNA analysis because of it’s short length STRs can be more easily recovered from the often degraded and limited quantities of DNA typically found in evidence FBI uses 13 core STRs for identification An individual’s DNA STR profile is unique

DNA Identification STR (short tandem repeat) continued You inherit one allele from each parent for each STR locus Homozygous Genotype (AA or aa): when one individual has 2 alleles that are the same for a specific STR Example: BB genotype (B allele is for brown eyes); the person has brown eyes (each B was inherited from a parent) Heterozygous Genotype (Aa): when a person has 2 different alleles for a particular STR Mom has B allele for brown hair, Dad has b allele for green eyes; child has Bb genotype but has brown eyes because B is dominant

You can locate each of the 13 core STRs used by the FBI; the AMEL on the sex chromosomes is not an STR

Collection of DNA Evidence Contamination of DNA evidence can occur when DNA from another source is mixed with the collected DNA Avoiding Contamination Wear gloves and change them often Avoid touching the area where you believe DNA exist Avoid talking, sneezing or coughing over evidence Avoid touching your face, nose and mouth when collecting and packaging evidence Air dry evidence thoroughly before packaging Keep evidence dry and cool during transportation and storage

Check for Understanding 2 Isolating and analyzing the variations Heterozygous genotype looks like… Most useful method of DNA analyzing 2 alleles that are the same for a specific STR Variations found in our DNA are found in this part of the DNA 3 ways to avoid contaminating the DNA Method mostly used for determining inheritance Check for Understanding 2

Steps of DNA Fingerprinting Extraction DNA is extracted from cells Restriction Fragments DNA is cut by restriction enzymes Restriction Enzymes: molecule that cuts a DNA molecule at a specific base sequence Amplification Specifically chosen DNA fragments are amplified using polymerase chain reaction (PCR) Electrophoresis Different sized DNA fragments are separated in an agarose gel Shortest DNA fragments travel further down the gel

DNA Fingerprinting Analysis and Application Matching DNA bands have the same width and travel the same distance through the electrophoresis gel Every state maintains a DNA index of individuals convicted of crimes like rape, murder, child abuse, etc. Results of DNA fingerprint analysis on electrophoresis gel

DNA Fingerprinting Analysis and Application DNA found at a crime scene is input into CODIS to identify possible suspects Ways DNA fingerprinting is used: Crime scene DNA matching with suspect’s DNA Paternity and maternity determination Identify family members and relatives Suspect elimination Freeing the falsely accused and imprisoned Identification of human remains

Check for Understanding 3 4 steps of DNA fingerprinting Used to amplify DNA fragments 2 ways which DNA fingerprinting is used The 2 things which tell you that you have matching DNA Cuts DNA molecules at a specific base True or False: The longer the DNA fragment the further down the gel it travels