What do you mean by DNA fingerprinting? Explain it through RFLP.
DNA fingerprinting is a technique developed by Sir Alec Jeffreys in 1984 at the University of Leicester to study and compare inherited variations in human DNA without sequencing. It exploits stretches of mini-satellite DNA known as Variable Number Tandem Repeats (VNTR) that are tandemly arranged in the genome.
The technique is performed using Restriction Fragment Length Polymorphism (RFLP). In RFLP, restriction digestion of DNA is carried out. We carry two different copies of every VNTR locus because we inherit one chromosome from mother and one from father. After restriction enzyme digestion of an individual's DNA in specific regions, unique patterns are generated for genetic analysis and identification.
The steps involved are: First, DNA is isolated from samples like blood, hair, skin, semen, or buccal swab. The collected DNA is cut into fragments using restriction enzymes. These fragments are separated by agarose gel electrophoresis based on size. The separated DNA is transferred to a nitrocellulose/nylon membrane and exposed to UV radiation or baked to permanently attach the DNA.
Southern hybridisation is then performed using VNTR probes (labeled stretches of single-stranded DNA) to detect complementary target sequences. The hybridised DNA fragments are detected, producing a pattern of bands characteristic to every individual.
Polymerase Chain Reaction (PCR) is often used to increase sensitivity by amplifying DNA. Applications include ascertaining paternity and maternity cases, and criminal identification and forensic studies by comparing VNTR patterns from crime scenes with suspects.
Explanation
This answer covers the definition, developer, and core concept of DNA fingerprinting using VNTR. It explains RFLP as the method involving restriction digestion that creates unique patterns. The step-by-step process is detailed: DNA isolation, restriction enzyme cutting, gel electrophoresis, membrane transfer, Southern hybridisation with VNTR probes, and detection. The role of PCR in amplification and key applications in paternity disputes and forensics are included. All information is drawn directly from the textbook context.