Question

In electrophoresis of suspect DNA in the crime scene, what does it mean when when we say that DNA samples were fragmented? What would your gel look like if the DNA was not fragmented? Explain using scientific evidence (10 points)

Answer 1

The DNA molecule nothing but a chain of, sugars, and phosphates molecules found in every cell in our bodies. It contains a unique sequence which is different between any two people (other than twin). The process by which this uniqueness is detected is called DNA fingerprinting. This method used to identify individuals by characteristics of DNA. Restriction enzyme cut the DNA chain in specific restriction sites. Location of these restriction sites are varied from person to person. As a result the fragments which are generated from the chain are varied in length. DNA samples were fragmented means the collected DNA sample of suspects is fragmented using a specific restriction enzyme. During, criminal investigation to identify a person or to locate a person at a crime scene, DNA fingerprinting is used globally in forensic science. In this process, the DNA is extracted from any collected specimen (like blood, semen, skin, hair). After that, restriction enzymes are added to the sample to cut the DNA into the smaller segments that are different between individuals. The DNA segments are analysed by agarose gel electrophoresis and visualized by staining with ethidium bromide. Each individual has a signature fingerprint.

If, the DNA sample is not fragmented by using a restriction enzyme then a single band appears in the gel after ethidium bromide staining.