Download Forensics Journal

Forensics Investigative Team
Case Journal
1.
Court Order
2.
Case 3425678 – Mystery Donor
3.
Hand Size Measurements
4.
Eye Color Analysis
5.
DNA Testing
6.
Possible Donors’ Information
7.
Final Report to Lottery Committee
Case 3425678 Overview:
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A county custodian found an unsigned Winning Lottery Ticket in an envelope taped to court house door,
he turned this envelope into his manager who in turn passed it onto the city manager.
The envelope included a letter that read:
o “I have been given many gifts in my life. But yesterday I was given an unusual gift – that of
winning the lottery. After many hours of contemplation, I decided that I did not want to keep New
York. As a courtesy, the finder of this ticket should receive a ‘finders-fee’ equal to 10% of
proceeds.”
State law requires that in order to redeem winning lottery tickets, the ticket must be signed.
The city manager petitioned the state courts to allow the city to redeem the gifted ticket, but the court
ordered that the mystery donor must be found to sign the ticket.
The court approved forensic testing in order to find the donor.
Case 3425678 Forensics Overview:
The Miami City Police Department was able to collect the following:
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A palm print was reconstructed from prints on the letter. It measured approximately 20 cm. in length and
11.5 cm. wide.
A DNA sample was obtained from a drop of blood found on the edge of the letter.
After reviewing security camera footage, it was determined that everyone who visited the courthouse
between 12:00 AM and 8:00 AM had lighter colored eyes (green, hazel, blue).
After reviewing the security camera footage, the Police Department utilized the FBI’s facial recognition
software and Biogenetics Database to create profiles for possible donors.
Case 3425678 Team Objectives:
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Review and analyze the forensics data collected by the Police Department
Determine the identity of the mystery donor from the available forensics data
Create a final recommendation report for City Manager
Possible Donor Information Derived from FBI Databases
Subject
Genetic
Condition
Description
Hand Size
Eye Color Alleles
Trisomy 21
(Down
Syndrome)
Extra
chromosome
(21)
L 18 cm
W 13 cm
bb/Gg
Trisomy 21
(Down
Syndrome
Extra
chromosome
(21)
L 25 cm
W 17 cm
Bb/Gg
None
None
L 24 cm
W 15 cm
bb/GG
47,XXY
(Klinefelter
Syndrome)
Extra X
chromosome
L 23 cm
W 16 cm
bb/GG
None
None
L 25 cm
W 18 cm
bb/gg
45,X (Turner
Syndrome)
Single X
chromosome
L 19 cm
W 12 cm
bb/GG
Tonia (left)
Tony (right)
Sebastian
Brian
Sara
Anita
Test 1:
Hand Size Analysis
Differences in Similar Phenotypes
NGSSS:
SC.912.L.16.1 Use Mendel’s Laws of Segregation and Independent Assortment to analyze patterns
of inheritance. AA
SC.912.L.16.2 Discuss observed inheritance patterns caused by various modes of inheritance,
including dominant, recessive, co-dominant, sex-linked, polygenic, and multiple alleles.
Background:
Humans are classified as a separate species because of all the special characteristics that they
possess. These characteristics are controlled by strands of DNA located deep inside their cells. This
DNA contains the code for every protein that an organism has the ability to produce. These proteins
combine with other chemicals within the body to produce the cells, tissues, organs, organ systems, and
finally the organism itself. The appearance of these organs, such as the shape of one’s nose, length of
the fingers, or the color of the eyes is called the phenotype. Even though humans contain hands with
five fingers, two ears, or one nose, there are subtle differences that separate these organs from one
another. There are subtle differences in a person’s genes that allows for these different phenotypes. In
this lab, we are going to observe some of these differences in phenotype and try to determine why they
happened.
Problem Statement: Do all human hands measure the same?
Vocabulary: alleles, dominant, genotype, homozygous, heterozygous (hybrid), phenotype, recessive
Materials (per group):
 Metric ruler
 Meter stick
Procedures:
Hand Measurement:
All human hands look pretty much alike. There are genes on your chromosomes that code for the
characteristics making up your hand. We are going to examine two of these characteristics: hand
width and hand length.
1. Choose a partner and, with a metric ruler, measure the length of their right hand in
centimeters, rounding off to the nearest whole centimeter. Measure from the tip of the middle
finger to the beginning of the wrist. Now have your partner do the same to you. Record your
measurements in Table 1.
2. Have your partner measure the width of your hand, straight across the palm, and record the
data in Table 1. Have your partner do the same to you.
Table 1 - Group Data on Right Hand Width and Length – Google Sheet
Class Data: After the entire class has completed Table 1, have the students record their data on the
board in the front of the room. Use Table 2 below to record the data for your use. Extend the table on
another sheet of paper if needed.
Table 2 - Class Data on Right- Hand Width and Length – Google Sheet
Tabulate the results of your class measurements by totaling the number of males and females with
each hand length and width and entering these totals in the tables below.
Table 3 - Class Hand Length – Google Sheet
Table 4 - Class Hand Width – Google Sheet
In order to form a more accurate conclusion, the collection of additional data is necessary. The teacher
has the option to include the data from all the classes running this experiment. Below find tables that
will allow the tabulation of several classes of data.
Bar Graph the data from Tables 5 and 6, and then answer the questions that follow. Use the
measurements of the width and length as your independent variable and the number of times that
measurement appeared as your dependent variable.
Observations/Analysis:
1. Examine the graphs. What is the shape of the graph for hand length? What is the most
abundant measurement for hand length?
2. What is (are) the least abundant measurement(s)?
3. If we are to assign letters to represent the various lengths, what value(s) would we assign to
the dominant genotype (HH)? The recessive genotype (hh)? The heterozygous genotype
(Hh)?
4. What would be the phenotypic name for the (HH) genotype?
5. What would be the phenotypic name for the (Hh) genotype?
6. What would be the phenotypic name for the (hh) genotype?
7. What is the shape of the graph for hand width?
8. What is the most abundant measurement for hand width?
9. What is (are) the least abundant measurement(s)?
10. If we assign letters to represent the various widths, what value(s) would we assign to the
dominant genotype (WW)? The recessive genotype (ww)? The heterozygous genotype (Ww)?
11. What would be the phenotypic name for the (WW) genotype?
12. What would be the phenotypic name for the (Ww) genotype?
13. What would be the phenotypic name for the (ww) genotype?
14. Are there any similarities in the graphs of the two characteristics? If so, what are they?
15. Are there any differences in the graphs of the two characteristics? If so, what are they?
16. Is there a difference in the length and width of the male and female hand? Does the gender of
a person have an effect on the phenotype of a trait? Explain:
Conclusion:
Develop a written report that summarizes the results of this investigation. Use the analysis questions
as a guide in developing your report. Make sure to give possible explanations for your findings by
making connections to the NGSSS found at the beginning of this lab hand-out. Also, mention any
recommendations for further study in this investigation.
Test 2:
Eye Color Analysis
The Genetics of Eye Color
The genetics of blood type is a relatively simple case of one locus Mendelian genetics—albeit
with three alleles segregating instead of the usual two (Genetics of ABO Blood Types).
Eye color is more complicated because there's more than one locus that contributes to the
color of your eyes. In this posting the description will entail the basic genetics of eye color based on
two different loci. This is a standard explanation of eye color but, as we'll see later on, it doesn't
explain the whole story. Let's just think of it as a convenient way to introduce the concept of
independent segregation at two loci. Variation in eye color is only significant in people of European
descent.
At one locus (site=gene) there are two different alleles segregating: the B allele confers brown
eye color and the recessive b allele gives rise to blue eye color. At the other locus (gene) there are
also two alleles: G for green or hazel eyes and g for lighter colored eyes.
The B allele will always make brown eyes regardless of what allele is present at the other
locus. In other words, B is dominant over G. In order to have true blue eyes your genotype must be
bbgg. If you are homozygous for the B alleles, your eyes will be darker than if you are heterozygous
and if you are homozygous for the G allele, in the absence of B, then your eyes will be darker (more
hazel) that if you have one one G allele.
Here's the Punnett Square matrix for a cross between two parents who are heterozygous at
both alleles. This covers all the possibilities. In two-factor crosses we need to distinguish between the
alleles at each locus so I've inserted a backslash (/) between the two genes to make the distinction
clear. The alleles at each locus are on separate chromosomes so they segregate independently.
B/G
B/G
B/g
b/G
b/g
B/g
b/G
b/g
As with the ABO blood groups, the possibilities along the left-hand side and at the top
represent the genotypes of sperm and eggs. Each of these gamete cells will carry a single copy of the
Bb alleles on one chromosome and a single copy of the Gg alleles on another chromosome.
Since there are four possible genotypes at each locus, there are sixteen possible combinations
of alleles at the two loci combined. All possibilities are equally probable. The tricky part is determining
the phenotype (eye color) for each of the possibilities.
According to the standard explanation, the BBGG genotype will usually result in very dark
brown eyes and the bbgg genotype will usually result in very blue-gray eyes. The combination bbGG
will give rise to very green/hazel eyes. The exact color can vary so that sometimes bbGG individuals
may have brown eyes and sometimes their eyes may look quite blue. (Again, this is according to the
simple two-factor model.)
The relationship between genotype and phenotype is called penetrance. If the genotype
always predicts the exact phenotpye then the penetrance is high. In the case of eye color we see
incomplete penetrance because eye color can vary considerably for a given genotype. There are two
main causes of incomplete penetrance; genetic and environmental. Both of them are playing a role in
eye color. There are other genes that influence the phenotype and the final color also depends on the
environment. (Eye color can change during your lifetime.)
One of the most puzzling aspects of eye color genetics is accounting for the birth of browneyed children to blue-eyed parents. This is a real phenomenon and not just a case of mistaken
fatherhood. Based on the simple two-factor model, we can guess that the parents in this case are
probably bbGg with a shift toward the lighter side of a light hazel eye color. The child is bbGG where
the presence of two G alleles will confer a brown eye color under some circumstances.
Posted by Larry Moran at 11:30 AM
Labels: Biochemistry, Science Education
http://sandwalk.blogspot.com/2007/02/genetics-of-eye-color.html
Test 3:
DNA Analysis
Making Karyotypes
(Adapted from: Prentice Hall, Lab Manual A)
NGSSS:
SC.912.L.16.10 Evaluate the impact of biotechnology on the individual, society and the environment,
including medical and ethical issues. AA
HE.912.C.1.4 Analyze how heredity and family history can impact personal health.
(Also addresses SC.912.L.14.6)
Background:
Several human genetic disorders are caused by extra, missing, or damaged chromosomes. In order to
study these disorders, cells from a person are grown with a chemical that stops cell division at the
metaphase stage. During metaphase, a chromosome exists as two chromatids attached at the
centromere. The cells are stained to reveal banding patterns and placed on glass slides. The
chromosomes are observed under the microscope, where they are counted, checked for abnormalities,
and photographed. The photograph is then enlarged, and the images of the chromosomes are
individually cut out. The chromosomes are identified and arranged in homologous pairs. The
arrangement of homologous pairs is called a karyotype. In this investigation, you will use a sketch of
chromosomes to make a karyotype. You will also examine the karyotype to determine the presence of
any chromosomal abnormalities.
Problem Statement: Can chromosomal abnormalities be observed?
Safety: Be careful when handling scissors.
Vocabulary: centromere, chromosomes, chromatids, genes, homologous pairs, karyotype, mutations,
Trisomy 21- Down syndrome, Klinefelter syndrome, Turner syndrome
Materials (per individual):
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Scissors
Glue or transparent tape
Procedures:
Part A. Analyzing a Karyotype
1. Make a hypothesis based on the problem statement above.
2. Observe the normal human karyotype in Figure 1. Notice that the two sex chromosomes, pair
number 23, do not look alike. They are different because this karyotype is of a male, and a
male has an X and a Y chromosome.
3. Identify the centromere in each pair of chromosomes. The centromere is the area where each
chromosome narrows.
4. Observe the karyotypes in Figures 4 and 5. Note the presence of any chromosomal
abnormalities.
5. Comparing and Contrasting: Of the three karyotypes that you observed, which was normal?
Which showed evidence of an extra chromosome? An absent chromosome?
6. Formulating Hypotheses: What chromosomal abnormality appears in the karyotype in Figure
4? Can you tell from which parent this abnormality originated? Explain your answer.
7. Inferring: Are chromosomal abnormalities such as the ones shown confined only to certain
parts of the body? Explain your answer.
8. Using the incomplete chromosomal analysis provided by the lab, determine the probable
identity of the mystery donor.
Results/Conclusions:
1. Draw a data table in the space below in which to record your observations of the karyotypes
shown in Figures 1, 4, and 5. Record any evidence of chromosomal abnormalities present in
each karyotype. Record the genetic defect, if you know it, associated with each type of
chromosomal abnormality present.
2. Drawing Conclusions: Are genetic defects associated with abnormalities of autosomes or of
sex chromosomes? Explain your answer.
3. Posing Questions: Formulate a question that could be answered by observing chromosomes
of different species of animals.
Sample DNA collected from the letter:
DNA Samples for possible Donors:
(Tonia)
(Ted)
(Sebastian)
(Brian)
(Sara)
(Anita)
Final Report:
Recommended Identity of
Mystery Donor
Recommendation of Donor Identity Summary:
Recommended Identity of Mystery Donor:
Evidence Supporting Identification of Mystery Donor:
Final Rational for Recommendation: