DNA Fingerprinting
DNA profiles identify individuals.
About this topic
DNA profiling identifies individuals from the unique pattern of repeated short sequences (STRs) in their DNA. DNA is extracted, amplified using PCR, cut or measured, and separated by gel electrophoresis, producing a barcode-like pattern; the closer the match, the more probable it's the same person.
It is used in forensic investigations, paternity tests, identifying remains and conservation. Identical twins share DNA profiles. Results are expressed as probabilities, and databases raise privacy concerns.
In a criminal case, DNA from a blood stain is compared to a suspect's. Everybody's STR lengths differ, so the pattern of bands on a gel is almost unique except for identical twins. Gel electrophoresis works because DNA is negatively charged, so fragments move toward the positive electrode, with smaller pieces travelling farther.
Besides forensics, profiling is used in paternity tests, identifying disaster victims, tracing the ancestry of animals and confirming the origin of foods. In 1984 Alec Jeffreys developed the method in Leicester, and in 1986 it helped to clear an innocent man and catch a murderer. Students commonly believe the test proves guilt with certainty; it gives a statistical probability, and contamination or poor sampling can mislead.
Key ideas
- Repeating sequences vary
- Gel electrophoresis separates fragments
- Used in forensics and paternity
Quick check
Use cases: where DNA Fingerprinting helps
- Homework: review the key idea behind DNA Fingerprinting before you start a problem set.
- Exam revision: use the quick check to test whether you can recall DNA Fingerprinting without notes.
- Visual learning: play with the interactive lab to see how DNA Fingerprinting changes when you adjust its inputs.
- Teaching a friend: explain DNA Fingerprinting in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is DNA Fingerprinting?
DNA profiles identify individuals.
What will I learn in DNA Fingerprinting?
Repeating sequences vary. Gel electrophoresis separates fragments. Used in forensics and paternity.
Is DNA Fingerprinting part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the DNA Fingerprinting lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study DNA Fingerprinting?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.