Abstract: DNA fingerprinting is a key aspect in the field of biological studies, especially in the specialty of forensics. The process of DNA fingerprinting is a procedure by which a sample of DNA has its base pairs, adenine, thymine, guanine, and cytosine, compared to other samples in order to find a match. Although humans in general have very high number of the same DNA sequences within their genome, there are areas within the DNA that vary enough to compare unless they are from monozygotic twins. Some instances where this process is used are during criminal investigations and for parental testing. The experiment conducted used the scenario of a single crime scene along with five different suspects. The samples underwent a restriction digest with the restriction enzyme mix of EcoRI and PstI. An electrophoresis through agarose gel allowed the suspects to be compared to the original crime scene in order to find a match. The culprit of the crime was suspect number 3.

Introduction: DNA fingerprinting, also known as DNA profiling is a method of identification that compares different fragments of DNA in order to find one that matches or is similar to an original sample (1). In order to gain a full understanding of DNA fingerprinting, one must have an understanding of DNA. DNA, deoxyribonucleic acid, contains every living organism’s genetic blueprint, which will determine everything for that individual from the looks to the personality and biological functions (2). DNA is composed of four different nitrogenous base pairs, adenine, guanine, cytosine, and thymine. Depending on the way each of these base pairs are ordered, determines everything (2). Adenine and guanine are known as the purines and can only bind together, while cytosine and thymine, the pyrimidines, can only bind together (2).
During DNA fingerprinting, DNA is obtained from different samples such as bodily fluids, hair, skin, and anything that contains ones genetic material (1). Although humans themselves are highly similar, close to 99%, there are still enough differences in ones genetic makeup (2). Each individual has their own genetic code unique to them except for monozygotic twins. The human genome is comprised of about 6 billion base pairs, since about 99% of these are identical in all humans; each person has their own distinct genome (3). At specific sites on certain chromosomes, an individual has a different nucleotide sequence, known as DNA polymorphisms (3). A form of a DNA polymorphism is called a single nucleotide polymorphism, SNP (4). These differences in DNA sequences are thought to have been fueled by mutations and changes cause by substitutions, deletions, or insertions in the code (1).
There are three major kinds of DNA fingerprinting. The first is restriction fragment length polymorphisms (RFLPs) (4).The second is variable number of tandem repeats (VNTRs), and the last is short tandem repeats (STRs) (4). Each of the three kinds of fingerprinting techniques has its advantages and disadvantages. The technique used for evaluating the crime scenes in this experiment was RFLPs. RFLPs uses restriction enzymes to cut a sequence of DNA at a particular site (1). This will form different lengths of fragments between each sample allowing them to be analyzed. Restriction enzymes are endonucleases that cut into the DNA sequence at a specific site (1). EcoR, which was used in the experiment, is designed to cut DNA fragments at the sequence of –GAATTC-. Since individuals have differing sequences, the polymorphisms were cleaved at different areas leading to different fragment lengths (4).
There are many different and very important uses for DNA fingerprinting. In the field of forensics, DNA fingerprinting can help either convict a criminal or exonerate an innocent individual who has been accused of a crime. Ones DNA will be compared to DNA found at a crime scene in order to distinguish if they are innocent or guilty. Since this is a relatively new