Process of Genetic Profiling (WJEC GCSE Biology): Revision Note

Process of Genetic Profiling

• Genetic profiling (DNA profiling) enables scientists to identify individuals based on their unique DNA 

• Every person (apart from identical twins) has a DNA profile which is unique to them

  • The more closely related you are to a person the more similar your genetic profiles are

• To create a DNA profile from a sample of DNA, scientists complete the following in sequence:

  • Obtain the DNA, which can be extracted from the root of a hair, a spot of blood or semen or saliva

  • Use enzymes to cut the DNA into fragments of different sizes

    • The sizes of the fragments are different for each person due to the unique nature of DNA

  • Separate the fragments using gel electrophoresis

    • DNA is suspended in an alkaline (agarose) gel

    • An electrical current is run through the gel

    • DNA is negatively charged and so moves toward the positive end of the gel 

    • Smaller fragments travel faster than larger fragments

  • The profile is then treated so that the fragments of DNA can be seen in bars (the DNA profile)

  • The pattern of the DNA profile is then analysed

The process of genetic profiling diagram

Gel electrophoresis is used to create genetic profiles by separating the fragments of DNA from a sample