Download Forensics of DNA

Name ________________________________________
Date ________________
Forensics of DNA
Go online to http://www.dna.gov/basics/analysishistory and complete
the following worksheet.
HISTORY OF DNA ANALYSIS
1.
_______________________________or DNA typing (profiling) as it is
now known, was first described in ______ by an English geneticist
named _________________________.
2.
Dr. Jeffreys found that certain regions of DNA contained
________________________________ that were repeated over and over
again next to each other. He also discovered that the number of
repeated sections present in a sample could differ from individual
to individual. By developing a technique to examine the length
variation of these DNA repeat sequences, Dr. Jeffreys created the
ability to perform ____________________________.
3. These DNA repeat regions became known as __________, which stands
for ____________________________________. The technique used by Dr.
Jeffreys
to
examine
the
VNTRs
was
called
_________________________________________ (RFLP) because it involved
the use of a ____________________________to cut the regions of DNA
surrounding the VNTRs.
4. Today over _________ public forensic laboratories and several dozen
private
paternity
testing
laboratories
conduct
________________________ of DNA test annually in the United States.
BIOLOGY OF DNA
1.
DNA is the abbreviation for _________________________________,
which is the genetic material present in the cells of all living
organisms.
2.
A
person's
DNA
is
the
same
in
every
___________
(___________________). The DNA in a person's blood is the same as
the DNA in their ___________________, _________________, and
________________________.
3. DNA is comprised of four building blocks called _______________.
The building blocks are: _________________, ___________________,
___________________,
_____________________.
These
are
commonly
referred to as ___, ___, ___, ____.
4. DNA is contained in________________________________________________
_____________________________________________________________________.
GATHERING DNA EVIDENCE
1
Name ________________________________________
1.
____________________________,
____________________________.
which
Date ________________
contains
DNA,
is
a
type
of
2. All biological evidence found at crime scenes can be subjected to
______________________.
IDENTIFYING DNA EVIDENCE
1. List where and what could be collected from a piece of physical
evidence that may lead to DNA evidence:
a.
b.
c.
d.
e.
hat __________________________,
envelope _____________________,
pillow _______________________,
fingernail ___________________,
soda can _____________________,
______________________________
______________________________
______________________________
______________________________
______________________________
CRIME SCENE INTEGRITY
1. While documenting evidence at the crime scene, include descriptions
of whether evidence was found ________ or ________. An example of
this documentation would include __________________________.
2. The risk of _____________________________ of any crime scene can be
reduced by limiting _________________________________. Because DNA
evidence is ___________________________than other types of evidence,
law enforcement personnel should be especially aware of their
actions
at
the
scene
to
prevent
inadvertent
_________________________________________________.
CHAIN OF CUSTODY
1.
The _______________________________ of evidence is a record of
individuals who have had ________________________ of the evidence.
______________________________ is critical to maintaining the
integrity of the chain of custody.
2. Because extremely small samples of DNA can be used as evidence,
greater attention to contamination issues is necessary when
_______________________,
________________________,
and
_________________________
DNA
evidence.
DNA
evidence
can
be
contaminated when DNA from another source gets mixed with DNA
relevant to the case.
TRANSPORTATION AND STORAGE
1.
As with any evidence, the officer should ensure that the
______________________________ is maintained. In addition, they
should
be
aware
that
__________________
and
_______________________________may degrade DNA, and avoid storing
2
Name ________________________________________
Date ________________
evidence in places that may get hot, such as the trunk of the police
car.
To
best
preserve
DNA
evidence,
store
in
a
_______________________________.
2. Any probative biological sample that has been stored _______ or
______________, regardless of age, may be considered for DNA
analysis. ____________________________ from blood and semen stains
more than 20 years old has been analyzed successfully using
_________________________________ (PCR).
3.
Samples
that
have
been
stored
_______for
an
_______________________________ should be considered for testing
only using ________ and may be unsuitable for DNA analysis.
___________________________________ has been performed on very old
bones, teeth, and hair samples.
ANALYZING DNA EVIDENCE
1.
Several basic steps are performed during DNA testing regardless of
the type of test being done. The general procedure includes: 1)
____________________________________________________________________
__________;2)
___________________________________________________;
3)_________________________________________; and 4) _______________
___________________________________________________________________
2.
Each additional test at a previously ______________________
(location or site) in the DNA provides another opportunity for the
result of "_________________________" if the known individual being
used for comparison is not the source of the DNA from an evidence
sample of unknown origin.
3. When a sufficient number of tests have been performed in which an
individual cannot be __________________ as the ______________ of the
DNA by any of the tests, a point is reached at which the tests have
excluded virtually the world's _____________________ and the unique
identification of that individual as the source of the DNA has been
________________.
4. Possible results from DNA testing include: 1) _______________; 2)
_________________; and 3) ________________.
5. _________________________ requires a biological sample about the
size of a quarter, but _____ can be used to reproduce millions of
copies of the DNA contained in a few skin cells.
6.
____________________________ (_____) technology is a forensic
analysis that evaluates specific regions (________) that are found
on nuclear DNA. The variable (________________) nature of the STR
regions that are analyzed for forensic testing intensifies the
discrimination between one DNA ___________ and another.
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Name ________________________________________
Date ________________
7. The Federal Bureau of Investigation (FBI) has chosen ____ specific
STR loci to serve as the standard for __________.
8.
Advancements in _______________________________ may eventually
eliminate the need for laboratories to extract and separate semen
and vaginal cells (for example, from a vaginal swab of a rape kit)
prior to analysis.
9.
_________________________
(mtDNA)
analysis
allows
laboratories to develop DNA profiles from evidence that
suitable for RFLP or STR analysis. While RFLP and PCR
analyze DNA extracted from the nucleus of a cell, mtDNA
analyzes DNA found in a different part of the
______________________.
forensic
may not be
techniques
technology
cell, the
10) Old remains and evidence lacking _______________________--such as
hair shafts, bones, and teeth--that are unable to be STR and RFLP
tested, may yield results if __________________ is performed. For
this reason, mtDNA testing can be very valuable to the investigation
of an _________________________.
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