DNA fingerprint patterns

Lanes 6, 7, and 8 contain DNA fingerprint patterns used as evidence in a rape case. Lanes 7 and 8 are DNA fingerprints of semen obtained from the rape victim. Lane 6 is the DNA fingerprint pattern of the... 

DNA fingerprinting is currently based on the analysis of autosomal short tandem repeats (STRs). STRs are DNA segments that are typically found in noncoding regions of genome and are composed of repeating units of 3-5 nucleotides sequence patterns. Because of their high mutation rate. 

In 1984, it was discovered that human genes contain short, repeating sequence of noncoding DNA, called short tandem repeats (STRs). The STR loci are slightly different for every individual except identical twins. By sequencing these loci, a unique pattern for each individual can be obtained. On the basis of this fundamental discovery, the technique of DNA fingerprinting was developed. 

Figure 15.27 Identical patterns shown by DNA fingerprinting can identify the criminal.

You may have heard that DNA fingerprinting is used in forensics to prove whether a suspect can be linked to a crime. There are other applications. Two people who are closely related to each other have DNA patterns that are more similar than the DNA of two unrelated people, so DNA is useful in identifying a person s family members and tracing heredity. Likewise, because species that share a common extinct ancestor have similar DNA patterns, scientists can track presumed evolutionary links. 

It takes a lot of DNA to make a DNA fingerprint. However, forensic applications of DNA fingerprinting can make use of a single hair, or the smallest trace of blood. Scientists can use small samples of DNA because they can rapidly copy, or amplify, DNA strands. By making many copies of a tiny sample of DNA, a scientist can make enough DNA to see the pattern of bases. 

DNA fingerprinting (genetic fingerprinting) The use of a pattern of DNA fragments obtained on restriction analysis of certain highly variable repeated DNA sequences, e.g. tandem repeat sequences which are virtually unique to an individual. This DNA profile , which can be detected in minute amounts of cells (e.g. in blood or semen), can be used in criminal cases and paternity suits. 

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