DNA Analysis And CODIS Essay Example

the highest degree of polymorphism are very useful for DNA analysis in forensics cases and paternity testing.

This activity is based on analyzing the inheritance of a class of DNA polymorphisms nown as "Short Tandem Repeats", or simply STRs. Short tandem repeat (STR) in DNA is a group of polymorphisms that occur when two or more nucleotides are repeated as well as those repeated sequences are directly adjacent to one another. This pattern can range anywhere from two to ten base pairs. By examining enough STR loci and counting how many repeats of a specific STR sequence there are at a given locus, it is possible to create a unique genetic profile of an individual.

There are currently over 10,000 published STR sequences in the human genome. STR analysis has become the prevalent nalysis method for determining genetic profiles in forensic cases. STR analysis has only been around for approximately ten years in the field of forensics. It is used for genetic fingerprinting of individuals. The STR’s that are used for forensic analysis are only tetra or penta ( 4 or 5 ) nucleotide repeat units. These are used because they offer more error free data and are capable of surviving degradation over time.

This includes exposure to very hot/cold elements, extremely long periods of time, and placement in under any other non idyllic conditions. In the United States, 13 core STR loci have been decided upon to be the basis by which an individual genetic profile can be generated. These profiles are stored on a local, state, and national level in DNA databanks such as CODIS. All CODIS STRs are tetrameric

repeat sequences and all forensic laboratories that use the CODIS system can contribute to a national database.

There are many advantages to the CODIS STR system including: STR profiles can be determined with minimal amounts of DNA, all data are digital and ideal for computer databases, labs all over the world can contribute to the nalysis of STR allele frequency in different human populations, STR alleles are discrete and behave according to known principles of population genetics and can be rapidly determined using commercially available kits, and the CODIS system has been widely adopted by forensic DNA analysts.

For each of the 13 genetic loci, a genotype is determined. The genotype is the allelic makeup of an individual such as homozygous dominant and recessive and heterozygous. Then the expected frequency of his genotype at each locus in a representative population sample is determined. By combining the frequency information for all 13 CODIS loci, one can calculate the frequency of a person’s genetic profile for example, 1 in 5 trillion Caucasians. Because there are fewer than 6 billion people on this planet.

DNA profiles can be instrumental in finding definitive matches that no one else can possibly share with the exception of an identical twin. This complicated world of DNA coding has been a lifesaver to those in law enforcement. Many years ago, criminals would be set free due to lack of eyewitness accounts or fingerprints. Nowadays, a simple fiber, strand of hair, saliva, or blood sample can yield DNA results that are undeniable in a court of law.

The advantages of CODIS and other databases are overwhelming. The instant access to

information can help in the quick apprehension of a criminal, the fact that it is much easier to identify repeat offenders in order to prevent future crimes, and the data base can also effectively eliminate suspects and end false arrests. Society greatly benefits from a DNA database of convicted criminals. There is nothing else like it in the fight against crime!