Download explaining the forensic use of dna to the average american

EXPLAINING THE FORENSIC
USE OF DNA TO THE AVERAGE
AMERICAN
Living Environment
January 8, 2011
Dr. Gregory De Angelo
Seton Catholic Central High School
[email protected]
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
http://www.publicdomainpictures.net/stock)
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
DNA Fingerprinting
II
DNA as Hereditary Material
A.
All human beings have 46 chromosomes
B.
Chromosomes are composed of genes
C.
D.
Genes are composed of DNA
DNA is composed of nucleotides. DNA is
the genetic material of the chromosome.
DNA Fingerprinting
Chromosome
“Non-sense” genes
Genes
DNA Fingerprinting
III
Chemical Structure of Nucleotides:
A.
B.
DNA is a polymer of nucleotides.
Each nucleotide has three parts
1.
2.
3.
C.
D.
A phosphate group (PO4)
A five carbon sugar - deoxyribose
A nitrogenous base
All DNA molecules have a phosphate and a
deoxyribose sugar.
Nucleotides differ according to their nitrogenous
bases.
1.
2.
Purines - Adenine and Guanine
Pyrimadines - Thymine and Cytosine (Uracyl
replaces Thymine in RNA).
DNA Fingerprinting
Q:
A:
What parts of the DNA are unique for
individuals and easy to measure?
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
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.
DNA Fingerprinting
E. 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
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.