Question Video: Determining What Samples Can Be Used to Identify a Victim of a Fire Biology

A man died in a fire and the police are trying to identify the body. After an initial inspection, it was found that the victim’s body was entirely burnt. Which of the following samples could the authorities use to search for the victim’s identity in their databases? [A] The victim’s fingerprints. [B] A DNA sample from the victim’s corpse. [C] A facial picture of the victim. [D] The victim’s footprints.

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Video Transcript

A man died in a fire and the police are trying to identify the body. After an initial inspection, it was found that the victim’s body was entirely burnt. Which of the following samples could the authorities use to search for the victim’s identity in their databases? (A) The victim’s fingerprints. (B) A DNA sample from the victim’s corpse. (C) A facial picture of the victim. (D) The victim’s footprints.

This question asks us about a way for authorities to identify a victim whose body has been completely burnt. Since the victim in our question had their entire body burned, we would not expect to be able to identify them based on their physical appearance. However, there are other ways to identify human remains through a process called DNA fingerprinting. This can be used because DNA is a very stable molecule.

We can do this by extracting the DNA from some of the cells of the victim’s body. This DNA contains a sequence of nucleotides that is unique to this particular individual. Special enzymes called restriction enzymes act as molecular scissors that can be used to cut the DNA at specific sites in the victim’s DNA. These cuts create fragments of DNA that are a specific size. These fragments and their size are unique to this individual. Another individual would have a different sequence of DNA that would create different fragment sizes after restriction enzyme cutting.

We can arrange these fragments based on their size using a technique called gel electrophoresis. This separates the fragments and creates a unique pattern that we call a DNA fingerprint. A different person would produce a different DNA fingerprint. Because this DNA fingerprint is unique to the burnt victim, it can be used to identify them from police databases.

Therefore, the sample that can be used to identify the burnt victim is given by answer choice (B): a DNA sample from the victim’s corpse.

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