lab 18 dna murder mystery
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Lab 18 DNA Murder Mystery. BY-102 Zach Nolen. DNA Fingerprinting. Is a technique used by forensic scientists to identify people based on their DNA profiles The key to DNA fingerprinting is Restriction Fragment Length Polymorphisms (RFLPs). When is it used?. Crime Investigations Rape - PowerPoint PPT PresentationTRANSCRIPT
Lab 18DNA Murder
MysteryBY-102
Zach Nolen
DNA Fingerprinting
0 Is a technique used by forensic scientists to identify people based on their DNA profiles
0The key to DNA fingerprinting is Restriction Fragment Length Polymorphisms (RFLPs)
When is it used?
0Crime Investigations0 Rape0 Violent Crimes
0Familial Relationships0 Paternity tests
How Specific Are RFLPs?
0Under normal circumstances, no other human has your exact complement of genes, unless…
0You are an identical twin
Murder Case
Murder Case
After going missing, Lynda Mann, a 15-year old schoolgirl was raped and murdered in the grounds of Carlton Hayes psychiatric hospital in Narborough, Leicestershire, in November 1983. Forensic examination of semen sample that it was a type found only in 10% of men, and was from someone with type A blood. However, the police did not find a suspect. In 1986, another 150year old schoolgirl, Dawn Ashworth, was similarly sexually assaulted and strangled in the nearby village of Enderby, and semen samples showed the same blood type.
Suspect 1
0Richard Buckland (17 years old)0 Local with learning disabilities0 Worked at Carlton Hayes psychiatric hospital0 Seen near murder scene of Dawn Ashworth0 Knew detailed information regarding body of deceased0 Confessed to the murder of Dawn Ashworth but not to
the murder of Lynda Mann
Suspect 2
0Colin Pitchfork (27 years old)0 Local baker0 Previous convictions for flashing0 Paid someone to give a false semen sample to police
during the investigation supposedly because of his prior convections.
How can we find the culprit?DNA Fingerprinting
Steps
1. Extract DNA2. Amplify DNA3. Cut DNA4. Sort DNA5. Denature DNA6. Hybridize DNA7. Make an X-Ray
Extract DNA
0We performed an extraction last week using cold ethanol. Keep in mind that there are other ways to extract DNA.
0We will be going through these steps using the DNA sheet that you should have printed out.
0 If you do not have the sheet, I have a few extras.
Amplify DNA
0We amplify DNA using Polymerase Chain Reaction (PCR).
0This allows us to increase the total amount of DNA that we have
0For our exercise, everyone having their copy of DNA will act as the amplification
Cut DNA0To cut DNA, Restriction enzymes are used.0These enzymes cut DNA by recognizing specific sites in
chains of DNA0We will act as restriction enzymes and cut our DNA at the
indicated sites.0 Make sure that the sites match exactly
NeoSci 15’ GG|CC 3’ 3’ CC|GG 5’
NeoSci 25’ GA|AG 3’3’ CT|TC 5’
Sort DNA
0After the DNA is cut using restriction enzymes, it must be sorted using gel electrophoresis
0This process separates DNA fragments based on size0We will cut paper DNA fragments out ant place them
on our paper gel0Fill out p. 215 by placing dark lines at any location
where a fragment would be present
Denature DNA
0After the DNA has been sorted, it must then be denatured using either heat or chemical.
0To denature our DNA, we will remove the yellow strips from the bottom of the fragments in our lanes
Hybridize DNA
0This step binds a radioactive probe to the fragmented DNA so that it can be seen.
0We will cut out the “T C C” probes and place them under fragments with the corresponding letters “A G G”
Make an X-Ray
0The process of taking an X-Ray of hybridized DNA is called Autoradiography
0Fill in lines on p. 214 to indicate fragments where hybridization has occurred.
Results
0Suspect 2: Colin Pitchfork is the murder.0Colin Pitchfork was the first person ever to convicted
of murder based on DNA fingerprinting evidence.
Paternity Tests
Review Questions
1. What is the key to DNA fingerprinting?2. What can DNA fingerprinting be used for?3. What do we use to cut DNA?4. How do we sort DNA?
Before you leave lab
0Clean up your work station
Before next lab
0Read Lab 7 – The Cardiovascular System0Do Online Prelab0Complete sections in lab manual for lab notebook
check