DNA fingerprinting Synonyms DNA Profiling DNA typing DNA testing

What is DNA fingerprinting A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA DNA fingerprinting is a method used to identify an individual from a sample of DNA by looking at unique patterns in their DNA.

DNA fingerprinting 99% of base sequences is same in the DNA of all human beings. Only a short stretches of sequences which is about 3 billion base pairs, differ from person to person. Out of total DNA, about 1 in 1000 base pairs is a site of variation in the population. This is an unusual sequences of bases of 10 -15 base pairs long which is repeated at several times, are called VNTRs.

Who Invented it? The process of DNA fingerprinting was invented by Alec Jeffreys at the University of Leicester in 1985.

DNA fingerprinting Variable number of tandem repeats (VNTRs) are the key for DNA fingerprinting because on the basis of number of repeats present in VNTRs, the length of segment is measured In different person the length of VNTRs differs The length of segments of DNA containing the repeated sequences is known as RFLP (Restriction Fragment Length Polymorphism )

Biological materials used for DNA fingerprinting Blood Hair Saliva Semen Body tissue cells

Stages of DNA fingerprinting 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)

Stages of DNA fingerprinting Step 2: The DNA is cut into fragments using restriction enzymes. Each restriction enzyme cuts DNA at a specific base sequence.

Stages of DNA fingerprinting 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).

Stages of DNA fingerprinting 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.

Stages of DNA fingerprinting 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.

Stages of DNA fingerprinting Thus obtained DNA segments are subjected to the south blotting The DNA bands appearing on membrane are hybridized with 32P- DNA probe Washed in water to remove the unhybridized DNA and passed trough X-ray

Stages of DNA fingerprinting 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.

Stages of DNA fingerprinting The pattern of fragment distribution is then analysed.

Uses of DNA fingerprinting DNA profiling is used to provide evidence in paternity and criminal cases and medical problems

THANK YOU -PHARMA STREET