1. Welcome back! Take out your notes from chapter 7: DNA Fingerprinting Analysis

2. Watson & Crick Discovered the basic shape of DNA
Won the Nobel Prize in 1953 for this discovery

4. From studies of DNA
we have found----
No two people have
identical DNA except..

5. Identical Twins
And they can be identified separately
by other means

6. DNA Fingerprinting Analysis
Can be used to match a suspect to a crime scene with a high degree of probability
Can be done on semen, saliva and blood
Can be performed on body cells

7. Sources of DNA
A perpetrator may leave biological evidence, such as saliva or blood, at a crime scene.
This individual evidence is capable of identifying a specific person.
But a small amount of biological evidence might be considered only trace evidence, and it may be consumed during forensic testing.
In 1993, however, the polymerase chain reaction (PCR) technique was invented. It generates multiple copies of DNA evidence.

8. Minute amounts of DNA
Can be amplified by PCR. This process allows the DNA to be copied many times so that a large enough sample is available for analysis

10. DNA analysis requires Obtaining a sample for analysis
Extract DNA and amplify it (PCR)
Cut the sample with digestive enzymes called restriction endonucleases

13. Variable Number of Tandem Repeats (VNTR)
DNA Identification
The number of copies of the same repeated base sequence in DNA varies among individuals.
Variable Number of Tandem Repeats (VNTR)
Within junk DNA, sequences of DNA are repeated multiple times.
Some can be 9-80 bases in length.
Short Tandem Repeats (STR)
Within junk DNA, other sequences of DNA also are repeated multiple times.
These usually are only 2-5 bases in length and are becoming the preferred sequences for analysis.

14. DNA Profiling and DNA Population Databases
VNTR and STR data are analyzed for (a) tissue matching and (b) inheritance matching.
Population genetics is the study of variation in genes among groups of individuals.
Calculations can be made based on these groups to determine the probability a random person would have the same alternative form of a gene (an allele) as (a) a suspect in a crime or (b) an alleged father in a paternity case.

15. Place the cut DNA in an electrophoresis chamber and conduct a separation
Compare the results of the separation to samples from various suspects

17. Running a Gel

18. Gel Electrophoresis Click on me, them click menu
Click on me, them click menu
Then ‘view the process of electrophoresis’

19. How to cut DNA Click on me, them click menu
Click on me, them click menu
Then ‘view how to cut DNA for
gel electrophoresis’ and follow directions

20. How to sort DNA by size Click on me, them click menu
Click on me, them click menu
Then ‘explanation of how molecules
can be sorted using a gel’..
and follow directions

21. Run a gel
Compare the results and determine whether the suspect was linked to the victim and crime scene.
Tagged samples are the evaluated. The tagging is done using a radioactive ‘probe’ which binds to specific sequences on DNA
What do your results indicate?

22. Probes
DNA probes are used to identify the unique sequences in a person’s DNA.
Different DNA probes are made up of different synthetic sequences of DNA bases compli-mentary to the DNA strand.
The probe binds to complimentary bases in the strand (see the fragmentary DNA bands above).
In most criminal cases, 6-8 probes are used.

23. Who was at the crime scene?

24. A real DNA profile

25. Another ‘tagged’ Lane 1 crime scene Lane 2 Suspect #1 Lane 3 Control
Lane 4 standard
Lane 5 Suspect #2
Lane 6 Control
Suspect #1 or #2?

26. Analysis of DNA Fingerprints and Applications
Bands and widths are significant in matching samples of DNA.
DNA fingerprinting can (a) match crime scene DNA with a suspect, (b) determine maternity, paternity, or match to another relative, (c) eliminate a suspect, (d) free a falsely imprisoned individual, and (e) identify human remains.

30. Internet Search
Have any persons previously found guilty be proven innocent by DNA testing?
Research ‘The Blooding’
Research ‘The Fugitive’

31. Discussion in groups of 4
A. Should the government be able to have access to everyone’s DNA? Explain your point of view.
B. Should the DNA of relatives of convicted criminals be available?
C. Should we screen everyone’s DNA at birth to identify possible health issues?
D. Should we be allowed to genetically alter plants and animals to make food more desirable for humans?

32. Gattaca
Please respond to the scene and implications