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STR analysis is a tool in forensic analysis that evaluates specific STR regions found on nuclear DNA. The variable (polymorphic) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another. [3] Scientific tools such as FBI approved STRmix incorporate this research technique.
For example, the standard protocols for DNA fingerprinting involve PCR analysis of panels of more than a dozen VNTRs. RFLP is still used in marker-assisted selection. Terminal restriction fragment length polymorphism (TRFLP or sometimes T-RFLP) is a technique initially developed for characterizing bacterial communities in mixed-species samples.
The first true method of DNA profiling was restriction fragment length polymorphism analysis. The first use of RFLP analysis in forensic casework was in 1985 in the United Kingdom. [4] This type of analysis used variable number tandem repeats (VNTRs) to distinguish between individuals.
Before modern PCR methods existed, it was almost impossible to analyze degraded DNA samples. Methods like restriction fragment length polymorphism (RFLP), which was the first technique used for DNA analysis in forensic science, required high molecular weight DNA in the sample in order to get reliable data.
Simple Sequence Length Polymorphisms (SSLPs) are used as genetic markers with polymerase chain reaction (PCR). An SSLP is a type of polymorphism: a difference in DNA sequence amongst individuals. SSLPs are repeated sequences over varying base lengths in intergenic regions of deoxyribonucleic acid (DNA).
In forensic science, hybridization probes are used, for example, for detection of short tandem repeats (microsatellite) regions [9] and in restriction fragment length polymorphism methods, all of which are widely used as part of DNA profiling analysis.
Genetic markers can be used to study the relationship between an inherited disease and its genetic cause (for example, a particular mutation of a gene that results in a defective protein). It is known that pieces of DNA that lie near each other on a chromosome tend to be inherited together.
Minisatellites consist of repetitive, generally GC-rich, motifs that range in length from 10 to over 100 base pairs.These variant repeats are tandemly intermingled. Some minisatellites contain a central sequence (or "core unit") of nucleobases "GGGCAGGANG" (where N can be any base) or more generally consist of sequence motifs of purines (adenine (A) and guanine (G)) and pyrimidines (cytosine ...