Dna Fingerprinting Lab Report

Each person inherits two copies of these markers from his or her mother and father, so a higher similarity denotes a closer biological relationship. The probability of two samples matching is around one in a billion (dna.gov). DNA profiles are compiled by using gel or capillary electrophoresis to separate samples into a pattern distinctive of the subject’s DNA based on ionic charge, size, or mobility. Usually, samples in the database are searched at moderate stringency, which requires that all alleles between the two samples match, but the number of alleles can vary, accounting for DNA contamination or degradation. Partial, or candidate, matches are samples that have a similar number of alleles in the forensic profile but are not exact, and are used in familial DNA searching to find close biological relatives of the original forensic profile. Other evidence is used to determine relatives, including Y chromosome analysis, which traces family relationships based on the fact that the Y chromosome is transmitted directly between a father and his sons; age; and geographic location. The process is based on the principle that first-order relatives have closer DNA profiles than unrelated individuals, and also on the sociological assumption that criminal tendencies appear in families; according to “the Bureau of Justice Statistics Correctional Populations

DNA forensics is a division of forensic science that focuses on the use of genetic material in criminal investigation to answer questions pertaining to legal situations, including criminal and civil cases. Through DNA testing, law enforcement officers are able to identify human remains or the individual responsible for a crime. DNA testing is a highly advanced scientific process that involves replicating the human DNA sequence to create a genetic map of an individual. Because of its reliability, DNA testing has become a significant factor in criminal cases. However, it has also been identified as having the potential to violate privacy and constitutional rights. The DNA identification process consists of five stages. These five stages

DNA analysts have been profiling DNA since 1985. Then in 1998, the Combined DNA Index System became fully operational (“FAQs” 2010). CODIS’s three levels are the national level, the state level, and the local level. As September 2015, there is 14,740,249 DNA profiles in CODIS (“CODIS”, n.d.). Since everybody has different DNA, except identical twins, DNA analysts have been able to assists with investigator to determine between who is guilty and who is innocent. With some of their findings, they are able to exonerate individuals, who have been wrongfully convicted. Even though television may make DNA analysts’ life look simple on the screen, it is not. There is need for interest and education. Lastly, the actual job that entails for the DNA

suspects in a case, an analyzed DNA sample from the crime scene does not significantly help

III. Today I will discuss how DNA is tested, how reliable DNA evidence is, and contamination issues that could arise in DNA evidence.

Beginning in the mid-1980s, the development of DNA analysis technology has revolutionised the field of forensic science within the criminal justice system. As the refinement of procedures and technology continues, even minute samples of biological material (including blood, saliva, semen and skin cells) are able to be analysed and used to link or acquit perpetrators of crimes. (Whitney, R n.d.)

DNA testing is a critical and accurate tool in linking accused and even convicted criminals for crimes, and should be widely used to assess guilt or innocence before jail sentences are imposed. It was started up by scientists Francis C. Crick and James D, Watson in 1953 as they had described the uses, structures and purpose of the DNA “deoxyribonucleic acid” genetic fingerprint that contains organism information about an individual (testing

Today in the crime world, DNA evidence is strongly accepted in solving crime cases. This is all based in part by allowing a crime laboratory to have a designated unit whose main goal is to analyze DNA evidence to aid investigators with positive outcomes in crime case solving. With that being said we are going to discuss the functions of a DNA unit within a crime lab as well as address the vital role these units play in solving crime.

Due to the uniqueness of DNA it has become a powerful tool in criminal investigations

No two people, except identical twins, have identical DNA sequences, which makes DNA testing appealing to law enforcement. Two types of DNA testing include short tandem repeat and variable number tandem repeat. Short tandem repeat requires less DNA compared to variable tandem repeat, which is “useful when a sample has been degraded at the crime scene.” (“DNA Evidence”) Whilst DNA evidence is a useful weapon in solving crimes, it is not infallible; therefore, it needs to be used with caution, especially with partial DNA profile,

DNA forensics can also narrow down suspect pools, exonerate innocent suspects, and link crimes together if the same DNA is found at both scenes. However, without existing suspects, a DNA profile cannot direct an investigation because current knowledge of genotype-phenotype relation is too vague for DNA phenotyping. For example, a profile from a first time offender that has no match in any database may give the information that the criminal is a left handed male of medium stature with red hair and freckles. It would be impossible to interview every man who fits that description. However, with available suspects, DNA forensics has many advantages over other forms of evidence. One is the longevity of DNA. Although it will deteriorate if exposed to sunlight, it can remain intact for centuries under proper conditions (Sachs, 2004). Because DNA is so durable, investigators can reopen old cases to reexamine evidence.

Once the results of testing were completed in this case, it positively matched two of the six rapes being investigated. The problems associated with this technology were that no real national database that was established or in place for complete comparison, and the since the technology was considered being fairly new it would require it to go through an

Because there are many different types of crimes, it is often difficult to find enough physical evidence to convict a person. For example, in rape cases there is usually only a small amount of physical evidence, so cases are based on word alone. Because of DNA testing we can now take samples from the victim and attempt to match the results with those of the suspect. Therefore, DNA is sometimes the only real way of determining the guilt or innocence of a suspect without having any witnesses. Since many rape cases are left unsolved, DNA testing is believed to be the most accurate way of keeping sex offenders off the street. Because of the growing trend of using DNA in rape cases especially, a company in Brooklyn now advertises a small flashlight-like device intended to be used to jab at attackers in order to collect a sample of his skin for later use (Adler). According to a study by Joseph Peterson, with the Department of Criminal Justice at the University of Illinois, DNA evidence does not have a major impact on the decision to either convict or acquit

The results in this lab showed that suspect 2 was a match for the DNA found at the crime scene. This was determined by DNA fingerprinting. In this lab, the samples of DNA from two suspects and the DNA from the crime scene were cut with two different restriction enzymes and then the DNA was run through gel electrophoresis. The different restriction enzymes cut the DNA in different places, so when the DNA was run through the gel, the gel showed two fragments for each sample based on their size. The fragments shown are known as bands of DNA. These bands of DNA for each suspect were analyzed and compared with the bands of the DNA from the crime scene. The bands of DNA were compared based on the distance they traveled through the gel from the wells.

DNA profiling technologies have had a considerable impact on how forensic science and criminal investigation have been understood, carried out, and regulated in the last 25 years. Current methods of forensic DNA profiling (known also as DNA fingerprinting and DNA typing), based on Polymerase Chain Reaction (PCR) amplifications of a varying number of Short Tandem Repeat (STR) loci found at different locations on the human genome, are regularly described as constituting the “gold standard for identification” in contemporary society. Prior to the implementation of PCR based extraction and amplification methods in the 1990’s, the initial uses of DNA fingerprinting (based on Multiple and Single Locus Probes) were largely confined to reactive