DNA drawingDNA is a chemical that determines how we are. Even though, its structure is the same in every organism, so what makes the difference? The multiple combinations of its components. That means that each of us has an specific DNA. That’s how we can identify people, like a fingerprint. And that’s what DNA fingerprinting is about!

But DNA fingerprinting doesn’t compare all the DNA’s structure. Instead, it compares the different cuts made by restriction enzymes. For doing so scientists have to follow a complex process:

  • First the DNA is removed from the sample cells with chemicals (like we did in the lab).
  • Then the strands that form the double helix are separated.
  • Restriction enzymes are added to the DNA strand. These enzymes identify particular sequences in the DNA and cut them forming free lengths of genetic material.
  • The next step is to order the several fragments in length order. In thisElectrophoresis drawing process electrophoresis is used. Electrophoresis is made by applying an electric field to a fluid. This makes dispersed particles in the fluid to move. In this case, this results in the different DNA cuts moving towards one side depending on their molecular weight – the largest ones weight more so they won’t move as much as the others- .
  • After electrophoresis other enzymes are added. These enzymes make the DNA sequences visible when exposed in photographic paper (either due to radioactivity or to chemiluminiscent properties).

The process must be repited several times with different selections of enzymes to build up a detailed fingerprint.

DNA fingerprint

DNA fingerprinting has many applications:

  • Paternity and maternity: as some specific DNA patterns are inherited you can prove genetic relations between people (familiar relations).
  • Criminal Identification and Forensics: DNA from samples in a crime scene can be compared with the DNA of a criminal suspect.
  • Personal Identification: DNA can be used to identify yourself, but this doesn’t seem practical as the process is too complex and having a DNA database is expensive. 

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Post creators: Ruth Moreno & Ángela Sedeño

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