Download DNA FINGERPRINTING

DNA FINGERPRINTING
Problem: How can DNA be used for the identification of criminals?
Materials: Graph Paper
Procedure:
1. The accompanying table describes the pattern of genes and repeats of a particular
segment of DNA for five individuals. The information will be used to construct models
of the DNA segment for each of the five individuals.
Individual
1
G1
2
G1
3
G1
4
G1
5
G1
KEY: Gene =
G2
10R
G2
1R
G2
11R
G2
6R
G2
4R
G
Repeat =
G3
G3
G3
G3
G3
R
DNA
4R
15R
8R
2R
5R
Sequence
G4
G5
G4
G5
G4
G5
G4
G5
G4
G5
7R
3R
5R
9R
12R
G6
G6
G6
G6
G6
6R
2R
3R
7R
4R
G7
G7
G7
G7
G7
2. Take your graph paper and hold it vertical. Divide it evenly into 5 columns. Label each
column Individual 1, Individual 2, Individual 3, etc. Next to each individual’s #, pick a
name at random. Fill out the chart on your answer sheet.
3. Starting at the top, label the first box G1 and the second box down G2 for each
individual. All the individuals have the same first 2 genes.
4. For each repeat, label a box R. For example, if an individual has 7R, you would place
an R in the next 7 boxes below the previous gene.
5. Fill in the genes for all 5 individuals.
6. After all the genes are filled in, cut your graph paper so each individuals DNA is
separate.
7. Using a blank piece of graph paper, pick one individual to make a DNA electrophoresis
of.
8. Cut the individuals genes so that each gene is attached with its following repeated
genes. Meaning the G1 and G7 for each individual will be one box long.
9. On the blank graph paper, begin on the left hand side and align the longest repeated
gene section with the bottom of the graph paper (so the G is in the bottom square of
graph paper). Mark a line on the graph paper showing the height of that gene’s
portion. Next take the 2nd longest repeat gene and in the same column, mark a line
at the height of this gene. Continue this until all individuals’ genes are marked on the
graph paper. You should have 4 marks. At the top of this electrophoresis, write the
number and name of the individual.
10. Repeat step 7-9 for each individual. At the end you should have 5 individuals
electrophoresis on your graph paper.
11. Compare your electrophoresis with the DNA electrophoresis of the criminals to
determine if any individual committed a crime. Wrong or invalid accusations would
lead to false imprisonment and a termination of your job (paper). Record information
on your answer sheet.
12. Finish the conclusion/analysis questions.
DNA Fingerprinting
Attach your electrophoresis to this paper
1. Complete the chart
Individual #
Individual Name
Crime
1
2
3
4
5
Unknowns
-
2. Did any individual have the same fingerprint?
3. Why is it unlikely that 2 individuals would have the same DNA fingerprint?
4. If blood and hair samples are recovered at the scene of a crime, how could they be
used to make a positive identification of a criminal?
5. What characteristic differs from person to person, causing fragments to separate
differently during electrophoresis?
6. What would be the logical explanation for two individuals having exactly the same DNA
fingerprints?
7. Why is it more useful to differentiate between human DNA fragments based on the
number of repeats rather than by looking at the differences between the genes?
8. What makes this lab activity different from that used in a real DNA electrophoresis for
a criminal investigation?