Chapter 20: Problem 38

A lab technician sweeps his hair back while he prepares a sample for polymerase chain reaction (PCR). Later, the DNA fingerprinting tests of the sample indicate that the lab technician was at the scene of the crime. What other explanation is there for the results of the DNA test?

Short Answer

Expert verified

The other explanation for the results of the DNA test is the possible contamination of the sample. The lab technician inadvertently introduced his own DNA into the sample while sweeping his hair back. This might have led to the results indicating that he was at the scene of the crime, even though it may not necessarily be true.

Step by step solution

Understanding PCR and DNA fingerprinting

Polymerase chain reaction (PCR) is a method widely used in molecular biology to rapidly make millions to billions of copies of a specific DNA sample. DNA fingerprinting is a forensic technique used to identify individuals by characteristics of their DNA. It can be used to solve crime, in parentage testing, or to identify bodies.

Realisation of contamination

Given that the lab technician swept his hair back while preparing the sample for PCR, he inadvertently introduced his own DNA into the sample. Hair is one of the major sources of DNA, and a single hair follicle can contain enough DNA for PCR.

Alternate explanation for DNA test results

The DNA fingerprinting tests showed that the lab technician was at the scene of the crime. However, the presence of his DNA in the sample does not necessarily mean he was at the crime scene. It could simply be that the sample was contaminated with his DNA during preparation. This is a common and well-documented risk in forensic science.

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A lab technician sweeps his hair back while he prepares a sample for polymerase chain reaction (PCR). Later, the DNA fingerprinting tests of the sample indicate that the lab technician was at the scene of the crime. What other explanation is there for the results of the DNA test?

Short Answer

Step by step solution

Understanding PCR and DNA fingerprinting

Realisation of contamination

Alternate explanation for DNA test results

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