DNA, short for deoxyribonucleic acid, is the way DNA strands are constructed and encoded. This is used in all sorts of DNA analysis and is one of the tools used in DNA testing. It is used in all the various forms of DNA evidence and analysis and is used as a means of identifying individuals.
DNA remains invisible to the naked eye but can be detected by an electron microscope. This is so the test can accurately identify whether a sample is that of an individual or a related sample. The DNA samples are usually prepared at the laboratory, cleaned and then are placed in small tubes with holes punched through them. In this manner the DNA strands are visualized under the electron microscope and the positions of the various DNA strands and nucleotides are clearly identified.
DNA strands can be classified as single, paired and multi-stranded. The DNA from a single cell divides, then recombines and produces a new pair of copies of the DNA. Nucleotides are the chemical units, which are used to create the DNA strands.
DNA evidence can be taken from any source. Most commonly this evidence is collected from saliva, urine, hair, semen, blood and teeth. DNA evidence can also be used as evidence in a variety of other cases such as criminal profiling, dental records, blood type, eyewitness testimony, forensic records, etc.
DNA testing has become so popular that a wide range of DNA tests are now available in the market. This has resulted in more accurate results because no doubt about the identity of the suspect is allowed. But this also has led to the increased popularity of certain types of DNA tests, such as the two-nucleotide polymorphism (mtDNA) test and the long tandem repeat (LTR) test. There are different types of DNA tests and some involve direct testing of DNA and others involve indirect testing. Direct DNA testing is the most accurate form of DNA analysis because it involves immediate identification of the type of cells present in the samples. Indirect DNA tests involve testing of DNA in combination with known information such as maternally inherited DNA or derived DNA such as skin cells.
The DNA from saliva, blood and hair can be combined with other DNA to provide the best result. So in a way there is no shortage of DNA results even when there is no physical evidence of sexual intercourse.
The DNA evidence is subject to a certain amount of debate. Despite the controversy surrounding the science of DNA, DNA evidence has gained immense popularity and is used widely in courts of law all over the world. There are many ways in which the results of DNA testing can be obtained but the most commonly used is the mtDNA testing and the LTR testing techniques.