1. 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

2. Chapter 6: DNA Fingerprinting

3. 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

4. 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

5. 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

6. 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)

7. Chromosomes are composed of many DNA double helixes

8. 22 homologous pairs of autosomes followed by the 2 sex chromosomes

9. 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

10. 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

11. 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

12. 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

13. 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

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

15. 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

16. 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

17. 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

19. 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

20. 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

21. 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