DNA FINGERPRINTS. A DNA fingerprint is a pattern of bands made from specific DNA fragments of an individual’s DNA. DNA analysis can be used for the following:.
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A DNA fingerprint is a pattern of bands made from specific DNA fragments of an individual’s DNA.
1) The banding patterns of the DNA fragments from two different individuals may be compared to establish whether they are related. (…such as in establishing paternity).
2) DNA fingerprints of members of different species can be compared to determine how closely the species are related.(…such as in evolutionary biological studies)
3) Using DNA fingerprints to compare samples of blood or tissue found at a crime scene with a suspect’s blood sample may even help solve a crime (…such as in criminology & forensics)
May 3, 2011
1) DNA must be extracted for analysis. (DNA may come from people or other organisms, as well as specimens such as blood or other tissue residues, possibly left at crime scenes or on victims of crimes)
2) A DNA sample may be amplified. A small sample may be increased amount of DNA for testing through a procedure called polymerase chain reaction (PCR).
3) Sample DNA is cut into fragments of different sizes by restriction enzymes.
DNA is prepared for fingerprinting by using a process called restriction fragment length polymorphism (RFLP) which cut the DNA at specific nucleotide sequences.
The number of fragments and the length of each fragment varies from person to person. (Specific polymorphic regions are targeted. These regions vary in people)
4) The fragments of DNA are then separated using a technique called gel electrophoresis. It separates the fragments according to size and charge.
5) DNA fragments are split. Radioactive probes bind to complimentary, single chain, fragments of the DNA in the samples, forming visible bands when exposed to photographic film.
6) The exposed film is developed to reveal a DNA fingerprint. The bands can then be analyzed visually or with a computer.
The DNA fingerprinting technology compares small segments of DNA that tend to vary the most from person to person.
These segments are “noncoding” regions where DNA repeats over and over again.
The photograph shows 8 columns on a gel. Several of these columns contain DNA fingerprints of samples taken from a crime scene, a victim, and four suspects.