DNA Fingerprinting - definition and process
Definition
DNA fingerprinting, also known as DNA profiling or DNA typing, is a technique used to identify and analyze specific patterns in an individual's DNA. It involves comparing the genetic material of two or more individuals to determine if they share a common origin, such as a parent-child relationship or a match between a suspect and a crime scene sample.
The process involves extracting DNA from a biological sample, such as blood or saliva, and amplifying specific regions of the DNA using polymerase chain reaction (PCR) technology. The resulting DNA fragments are then separated and visualized using various techniques, such as gel electrophoresis or capillary electrophoresis.
The unique pattern of DNA fragments, called a DNA profile or DNA fingerprint, can be used to identify an individual with a high degree of certainty. DNA fingerprinting is widely used in forensic science, paternity testing, and medical research, among other fields.
Enzymes involved in DNA fingerprinting
Several enzymes are involved in the process of DNA fingerprinting. Here are some of the key enzymes and their roles:
Restriction enzymes: These are enzymes that cut DNA at specific sequences, called restriction sites. In DNA fingerprinting, restriction enzymes are used to cut DNA into fragments of different sizes, which can be separated and analyzed to create a DNA profile.
Polymerase chain reaction (PCR) enzymes: PCR is a technique used to amplify specific regions of DNA. PCR enzymes, such as Taq polymerase, are used to replicate the DNA fragments obtained from the biological sample, so that there is enough DNA to analyze.
DNA ligase: This enzyme is used to join DNA fragments together. In DNA fingerprinting, DNA ligase may be used to attach a fluorescent or radioactive label to the ends of the DNA fragments, which can then be visualized and analyzed.
Gel electrophoresis enzymes: Gel electrophoresis is a technique used to separate DNA fragments by size. Enzymes such as ethidium bromide or SYBR Green are used to visualize the separated DNA fragments under ultraviolet light.
These are some of the key enzymes involved in DNA fingerprinting. Other enzymes and chemicals may also be used depending on the specific method and application of the technique.
Step by step process of DNA fingerprinting
Here are the general steps involved in DNA fingerprinting:
- Collection of the biological sample: DNA is extracted from a biological sample such as blood, saliva, hair, or skin cells.
- Isolation of DNA: The DNA is isolated from the biological sample using a variety of techniques, such as cell lysis, centrifugation, and precipitation.
- Amplification of DNA: Polymerase chain reaction (PCR) is used to amplify specific regions of the DNA that contain short tandem repeats (STRs) or other genetic markers.
- Digestion of amplified DNA: The amplified DNA is then digested with restriction enzymes, which cut the DNA into fragments of different lengths.
- Separation of DNA fragments: The DNA fragments are separated using gel electrophoresis, which separates the fragments based on size. The fragments are then visualized using a fluorescent dye or radioactive label.
- Analysis of DNA fragments: The DNA fragments are compared to each other to create a DNA profile. The DNA profile is a unique pattern of bands that represents the individual's genetic makeup.
- Interpretation of DNA profile: The DNA profile is compared to DNA profiles from other individuals to determine if there is a match. The probability of a match is calculated based on the frequency of the DNA profile in the population.
- Reporting of results: The results of the DNA fingerprinting analysis are reported to the appropriate parties, such as law enforcement, medical professionals, or individuals involved in a paternity test.
These are the general steps involved in DNA fingerprinting. Different methods and variations of these steps may be used depending on the specific application of the technique.
Application of DNA fingerprinting
DNA fingerprinting has a wide range of applications in various fields, some of which include:
- Forensic science: DNA fingerprinting is extensively used in forensic science to identify suspects and link them to crimes. DNA profiles obtained from biological samples, such as blood, semen, hair, or skin cells found at a crime scene, can be compared to DNA samples from suspects or a DNA database to identify the perpetrator.
- Paternity and maternity testing: DNA fingerprinting can be used to determine the biological relationship between parents and children in cases of disputed paternity or maternity.
- Medical diagnosis: DNA fingerprinting can be used for medical diagnosis of genetic disorders or mutations. For example, the genetic mutations associated with certain types of cancer can be identified through DNA fingerprinting.
- Evolutionary biology: DNA fingerprinting can be used to study the evolutionary relationships between different species or populations by comparing their DNA sequences.
- Agriculture and livestock breeding: DNA fingerprinting can be used to identify specific plant or animal varieties and to trace the ancestry of a particular strain or breed.
- Historical and archaeological research: DNA fingerprinting can be used to study ancient DNA and to trace the lineage and migration patterns of humans and other species throughout history.
Overall, DNA fingerprinting is a powerful tool for identifying and analyzing genetic variation, and it has a wide range of applications in fields such as forensics, medicine, and biology.