40. DNA fingerprinting is used in many situations to help identify individuals. Analyze the situation below before answering the questions that follow.
A man was attacked and robbed, but remembers nothing of the incident because he fell and hit his head. He has numerous cuts and abrasions from the event, and blood was found under his fingernails. A piece of torn clothing with a bloodstain on it was also found at the scene.
Two people were seen near the crime scene. Both males, they say they don't know each other and just happened to be near the scene at the time of the attack. One of the males has a fresh scratch across his face, while the other male has a scratch on his right arm.
It's not clear from observations of the crime scene how many individuals were involved in the crime. Two males have reportedly been robbing individuals in the vicinity. There's a rumor that the two are brothers.
a. Explain two DISTINCT uses that DNA fingerprinting could be used for in this situation. In particular, what are two important issues that should be resolved to help clarify the identity of the individuals of the body fluids found at the scene?
My answer: Each individual, other than identical twins, has a unique DNA fingerprint. The banding patterns for the 2 men could be compared to establish whether they are brothers. Also, because it can be performed on a sample of DNA found in blood, like under the victim's fingernails, DNA fingerprinting is useful in forensics. Forensics is the scientific investigation of the causes of injury and death when criminal activity is suspected, like in this case.
b. How could you test one of these issues using DNA fingerprinting without using blood samples from the scene of the crime.
My answer: You can check if the 2 men are brothers by comparing their banding patterns.
Are my answers OK?
Thanks
-MC
Your answers are mostly correct, but I would like to provide some additional clarification.
a. DNA fingerprinting can be used in this situation for the following purposes:
1. Identification: DNA fingerprinting can help identify the individuals involved by comparing their DNA profiles to the DNA found at the crime scene. Each individual (except identical twins) has a unique DNA fingerprint, so comparing the DNA profiles of the two men to the blood and other bodily fluids found at the scene can help determine if they were present and potentially involved in the crime.
2. Establishing relationships: DNA fingerprinting can also be used to determine if the two men are brothers. By comparing their DNA profiles, it is possible to identify if they share common genetic markers, providing evidence for their relationship.
To clarify the important issues that should be resolved for DNA fingerprinting to help clarify the identity of the individuals, specifically related to the body fluids found at the scene:
1. Contamination: It is crucial to ensure that any DNA evidence found at the crime scene was not contaminated. Contamination can lead to misleading results and incorrect conclusions. Proper chain of custody procedures and strict laboratory protocols should be followed to minimize the risk of contamination.
2. Sample quality: The DNA samples retrieved from the scene, such as the blood found under the victim's fingernails, need to be of sufficient quality and quantity for successful DNA analysis. DNA can degrade over time or be diluted by other substances, so ensuring the samples are suitable for analysis is crucial. Proper collection, storage, and preservation methods should be implemented.
b. To test the issue of whether the two men are brothers using DNA fingerprinting without using blood samples from the crime scene, other biological samples can be collected and analyzed. For example, samples such as buccal swabs can be taken from the two men by gently swabbing the inside of their cheeks to collect cells containing DNA. These swabs can then be used to extract DNA and create their respective DNA profiles. By comparing their DNA profiles, it can be determined if they share common genetic markers, indicating a potential familial relationship.