DNA PROFILING
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DNA profiling is a technique used by scientists to distinguish individuals using DNA samples. It involves breaking down cells to extract DNA, amplifying small DNA samples, cutting the DNA into fragments using restriction enzymes, separating the fragments by size using gel electrophoresis to produce a fluorescent image of bands, and analyzing the pattern of fragment distribution.
DNA PROFILING
- 1. DNA PROFILING A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA
- 2. Stages of DNA Profiling
- 3. Stages of DNA Profiling • Stage 1: Cells are broken down to release DNA If only a small amount of DNA is available it can be amplified using the polymerase chain reaction (PCR)
- 4. Stages of DNA Profiling • Step 2: The DNA is cut into fragments using restriction enzymes. Each restriction enzyme cuts DNA at a specific base sequence.
- 5. Stages of DNA Profiling • The sections of DNA that are cut out are called restriction fragments. • This yields thousands of restriction fragments of all different sizes because the base sequences being cut may be far apart (long fragment) or close together (short fragment).
- 6. Stages of DNA Profiling Stage 3: • Fragments are separated on the basis of size using a process called gel electrophoresis. • DNA fragments are injected into wells and an electric current is applied along the gel.
- 7. Stages of DNA Profiling DNA is negatively charged so it is attracted to the positive end of the gel. The shorter DNA fragments move faster than the longer fragments. DNA is separated on basis of size.
- 8. Stages of DNA Profiling • A radioactive material is added which combines with the DNA fragments to produce a fluorescent image. • A photographic copy of the DNA bands is obtained.
- 9. Stages of DNA Profiling Stage 4: • The pattern of fragment distribution is then analysed.