A crime scene
This DNA profile shows a hypothetical example of how gene probes are used in
forensic investigations. In this case a victim was murdered. There are three
suspects under investigation. A blood sample was taken from the scene of the
crime. The blood is believed to belong to the attacker. Two fluorescent probes
were used to produce a DNA profile.
Adapted from an activity on p98 of
Microbiology and Biotechnology in
the Biology Modular Workbook
series.
Authors: Greenwood, Shepherd,
Allan, Butler.
Published in 2006 by Biozone
International Ltd.
Reproduced with the permission of Biozone International Ltd
Using the profile, answer the following questions.
1. Identify which of the three suspects was the likely killer.
2. What information from the profile helped you arrive at your answer?
3. Why would a sample be taken from the victim and analysed?
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4 Until DNA profiling was developed, blood types and fingerprints were used
as evidence to assist in the solving of crimes. Why is DNA profiling a more
reliable technique?
Scroll down for answers.
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A crime scene – Answers
1. Suspect 1.
2. The fluorescent bands on the profile from Suspect 1 and the evidence
matched.
3. To ensure the evidence was clearly a different DNA to the victim’s DNA.
4 This technique is based on very specific molecular information. The chance
of two people sharing similar microsatellites is approximately one in a billion,
so identification is very reliable.
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