History Of Dna And Its Application To Forensics Biology Essay


Deoxyribonucleic acid (DNA) is one of the main backbones in criminal investigations, and plays a very vital role in science and technology. DNA research has improve greatly since its discovery. Its purpose and application have been refined to serve the needs and requirements for modern day criminal justice technology.

Unremarkably known as DNA, deoxyribonucleic acid has played a vital role in the basis for a great deal of scientific work. This primal discovery was attributed to Francis Crick and James Watson. Numerous people believe Rosalind Franklin, along with Watson and Crick played critical role in the research. DNA is a long polymer composed of, repeating units called nucleotides. the structure of DNA consists of two helical chains each wrapped around the same access, Although DNA is very small, DNA polymers can be composed of very big molecules that contain millions of nucleotides.

In living organisms, DNA is not commonly known as a singular molecule, but instead as a partner of molecules that are bonded closely together. The repeating nucleotides carry the section of the backbone of the molecule, whose job is to hold the chains together, along with a base, that acts with the other DNA strand in the helix. A base which is linked to glucose is called a nucleoside and a base tied to a glucose along with one or more phosphate groups is called a nucleotide. If more than one nucleotide is linked together, like we see in DNA, this polymer is called a polynucleotide.

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The primary purpose of DNA would be information storage The nucleotides have 'backbones' connected to them composed of sugars and phosphates. Adjoined to each sugar molecule is a specified base “base refers to the 'basic necessity' of the component within the DNA chain, rather than any other chemical representationsâ€Â.These bases connect with each other during hydrogen bonds. It is the ranging of the bases which join the two polymer strands together that determines the overall natural features of the biological body in which that DNA exists. This is known as, genetic coding, where a life forms characteristics and physical traits are stashed away within the molecular formula of this specific macromolecule.

The secondary purpose of DNA would be RNA synthesis. DNA manages the synthesis of RNA with the chemical process known as transcription. During this process cellular enzymes are told by the genetic code to reanimate strands of RNA in relation to the coded sequences stored in the DNA itself. These strands, also referred to as mRNA (or Messenger Ribonucleic Acid), transport information regarding the genetic code into the protein making parts of the cell, where they jumpstart a key arrangement of amino acids inside of the protein assembly, which then controls the physiological features of the organism.

DNA typing, which was presented in the mid-1980s, has overturned forensic science and the ability of law enforcement to match crime scenes to the criminals. Thousands of cases have been closed and guilty perpetrators finally punished due to the power of a biological telltale witness at the scene. DNA fingerprinting known now as DNA profiling , was depicted in 1985 by an English geneticist named Alec Jeffreys. Jeffreys found that specific sections of DNA held DNA sequences that were continuously repeated over again next each other. He also discovered that the number of repeated sections demonstrated in a sample could vary from one to another. By generating a method to analyze the length variation of these DNA repeat sequences, Dr. Jeffreys produced the ability to perform human identity tests. DNA repeat regions now known as VNTRs, stands for variable number of tandem repeats. The technique Dr. Jeffreys used to analyze the VNTRs was named restriction fragment length polymorphism (RFLP) due to the fact that it required the use of a restriction enzyme to alter the areas of DNA bordering the VNTRs. This RFLP method was first used to aid in a case regarding English immigration then to solve a double homicide case shortly thereafter. Since then, the testing of human identity using DNA typing methods has been widely circulated. There has been tremendous growth the past fifteen years with the use of DNA in crime scene investigations along with paternity testing. Today over 150 public forensic labs and numerous private paternity testing labs perform hundreds of thousands of DNA test yearly in the United States. Also, most countries in Asia and Europe have forensic DNA programs. The number of laboratories around the world directing DNA testing will continue to develop as the technique gains in popularity within the law enforcement community.

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Any type of organism can be identified by analyzing DNA sequences unique to that species. Identifying individuals inside a species has proven to be less precise at this moment, although when DNA sequencing technologies due progress farther, direct comparison of very large DNA segments, and possibly even whole genomes, will become possible, as well as common and will allow exact individual identification. To distinguish individuals, forensic scientists scan 13 DNA regions, commonly known as loci, that change from one individual to another and use the information to produce a DNA profile of that individual often referred to as a DNA fingerprint. There is a very rare probability that two people will have the same DNA profile for a specified set of 13 regions. Just a few examples of how DNA is used in forensics would be to, identify possible suspects whose DNA may match evidence recovered at crime scenes, to clear people that have been wrongly accused of crimes, to identify unknown crime and disaster victims, establish paternity and other kin, identify protected and endangered species as an aid to wildlife officials also used for prosecuting poachers, Detecting bacteria along with other organisms that could possibly pollute food , soil ,air ,and water, pair organ donors with

recipients in transplant programs.

RFLP (Restriction Fragment Length Polymorphism) is a technique for analyzing the various lengths of DNA pieces that result from processing a DNA sample with a certain kind of enzyme. This enzyme, known as a restriction endonuclease, cuts DNA at a specific sequence pattern know as a restriction endonuclease recognition site. The absence or presence of certain recognition sites in a DNA sample bring forth various lengths of DNA fragments, which using gel electrophoresis separates them. RFLP was one of the first uses of DNA analysis in forensic investigations. RFLP is not used as much as it was before due to the development of newer, more thorough procedures, because it involves relatively large amounts of DNA. The next technique would be, Polymerase chain reaction (PCR) which is utilized to produce millions of exact templates of DNA from a biological sample. DNA amplification with PCR allows DNA analysis with samples as small as a few skin cells. On the other hand with RFLP, DNA samples would need to be around the size of a quarter. The ability of PCR to amplify extremely small quantities of DNA enables even highly devalued samples to be examined.. Next, there is STR Analysis Short tandem repeat (STR)analysis is used to assess certain loci within DNA inside of the nucleus. Variance in STR regions can be utilized to differentiate one DNA profile from another. The FBI uses a basic set of 13 specific STR regions for a software program that runs local, state, and national databases of DNA profiles from unsolved crime scene evidence, missing persons and convicted offenders, . The probability that two people will acquire the same 13-loci DNA profile is approximately one in a billion.

Past furtherance in DNA technology has bettered law enforcement's ability to utilize DNA to solve recent cases. Original forensic uses for DNA analysis were created using a technology known as restriction fragment length polymorphism. Even though cases over ten years old most likely did not have RFLP analysis done, in these days RFLP testing may have been rarely attempted on recent unsolved cases. On the other hand, because RFLP analysis required a very large amount of DNA, testing may not have been accurate. Likewise, biological evidence held insufficient in size for testing would not have been recently submitted for testing. Also, if a biological sample was lowered in worth by environmental factors such as mold or bacteria, RFLP analysis may have been unsuccessful at giving a reliable a result.

Newer technologies are now useful in gathering results. Advances in analysis techniques make it able for labs to compose profiles from bodily evidence that is unable to be seen with the naked eye, for example, skin cells that remained on ligatures or weapons. Unsolved cases should be analyzed by examining both nontraditional and traditional sources of DNA. Extremely useful DNA evidence might be assessable that was unknown or undetected during the primary investigation. If DNA evidence is being used for testing or retesting in unsolved cases and their investigations it is important that crime labs and law enforcement collaborate to work through logical issues pertaining to the access to and the cost of DNA analysis which is going to be a factor along with the power of each of the technologies that might affect the overall results.

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That is how, deoxyribonucleic acid (DNA) is one of the main backbones in criminal investigations, and plays a very vital role in science and technology. DNA research has improve greatly since its discovery. Its purpose and application have been refined to serve the needs and requirements for modern day criminal justice technology.