1. EXPLAINING THE FORENSIC USE OF DNA TO THE AVERAGE AMERICAN
Living Environment
January 8, 2011
Dr. Gregory De Angelo
Seton Catholic Central High School

2. PPA PROCESS
Q: What solution can be implemented that enable crime investigators to effectively use DNA “fingerprinting” into the judicial process?
A: Forensic experts must educate judges and juries about how the properties of each person’s DNA is unique to them and them alone.
PPA link (Wood Gavel And Sounding Block

3. DNA Fingerprinting I What is DNA?
A. Molecule that carries genetic material
B. It is the constituent of chromosomes and genes
C. It is composed of nucleotides

4. DNA Fingerprinting II DNA as Hereditary Material
A. All human beings have 46 chromosomes
B. Chromosomes are composed of genes
C. Genes are composed of DNA
D. DNA is composed of nucleotides. DNA is the genetic material of the chromosome.

5. DNA Fingerprinting
Chromosome
“Non-sense” genes
Genes

6. DNA Fingerprinting III Chemical Structure of Nucleotides:
A. DNA is a polymer of nucleotides.
B. Each nucleotide has three parts
1. A phosphate group (PO4)
2. A five carbon sugar - deoxyribose
3. A nitrogenous base
C. All DNA molecules have a phosphate and a deoxyribose sugar.
D. Nucleotides differ according to their nitrogenous bases.
1. Purines - Adenine and Guanine
2. Pyrimadines - Thymine and Cytosine (Uracyl replaces Thymine in RNA).

7. DNA Fingerprinting Q: What parts of the DNA are unique for
individuals and easy to measure?
A: It is impractical to every gene in our DNA to
the genes of others. Instead what is measured
are the “non-sense” genes (codes) that are
between each gene. These are called
restriction fragment length polymorphism or
RFLP

8. DNA Fingerprinting III RFLP
A. Series of triplet sequences that repeat numerous times.
B. The length of these sequences differ from individual to individual and are used as a means of DNA typing.
C. The length differences associated with DNA strands are called RFLP.
D. Once these sequences are cut, they are sorted out using electrophoresis.

9. DNA Fingerprinting Types of RFLPs 1. Long tandem repeats (LTR)
a. Regions of DNA that contain more than 7 repeating base
pairs.
b. Since they are long they are more subject to degradation
2. Short tandem repeats (STR)
a. Regions of DNA containing 3 to 7 repeating base pairs
b. Less likely to degrade
c. There is a greater variety of STRs

10. DNA Fingerprinting 6. Short Tandem Repeats
a. Definition: Regions of a DNA molecule that contain short segments consisting of three to seven repeating base pairs.
b. Used as markers because they are found in great abundance.
c. Since they are short, they are much less susceptible to degradation.
d. Hundreds of different types of STR’s
e. Multiplexing - Technique that simultaneously detects more than one DNA marker in a single analysis.
f. Amelogenin gene - A genetic locus found useful for determining gender.