Question

Describe about the DNA markers and their uses in Forensic cases.

Answer 1

DNA (deoxyribonucleic acid) is a molecule that is shaped like a double helix and made up of pairs of nucleotides, abbreviated as “A”, “C”, “G” and “T” DNA is packaged into chromosomes which are located within the nucleus of all cells. Every cell in the body contains all of the chromosomes that collectively make up the genome of that organism.

RFLP (Restriction Fragment length Polymerization): RFLP is a technique in which organisms may be differentiated by analysis of patterns derived from cleavage of their DNA. If two organisms differ in the distance between sites of cleavage of a particular restriction endonuclease, the length of the fragments produced will differ when the DNA is digested with a restriction enzyme. The similarity of the patterns generated can be used to differentiate species (and even strains) from one another.

Applications of RFLP:

RFLPs can be used in many different settings to accomplish different objectives.

 RFLPs can be used in paternity cases or criminal cases to determine the source of a DNA sample.

 RFLPs can be used determine the disease status of an individual.

 RFLPs can be used to measure recombination rates.

RAPD (Random Amplification of Polymorphic DNA): RAPD is a type of PCR reaction, but the segments of DNA that are amplified are random. The discovery that PCR with random primers can be used to amplify a set of randomly distributed loci in any genome facilitated the development of genetic markers for a variety of purposes. The main reason for the success of RAPD analysis is the gain of a large number of genetic markers that require small amounts of DNA.

SNP (Single nucleotide polymorphism) or where alleles differ from each other by the sequence of only a single nucleotide base pair. SNP genetic tests focus on detecting precise single nucleotide base pair differences among the three billion nucleotide base pairs that make up the bovine genome.

Microsatellites: are stretches of DNA that consist of tandem repeats of a simple sequence of nucleotides (e.g. “AC” repeated 15 times in succession). The tandem repeats tend to vary in number such that it is unlikely two individuals will have the same number of repeats. To date, the molecular markers used to determine parentage have primarily utilized microsatellite markers.