The Forensic Analysis Of Dna

This paper explores deoxyribonucleic acid (DNA) collection and its relationship to solving crimes. The collection of DNA is one of the most important steps in identifying a suspect in a crime. DNA evidence can either convict or exonerate an individual of a crime. Furthermore, the accuracy of forensic identification of evidence has the possibility of leaving biased effects on a juror (Carrell, Krauss, Liberman, Miethe, 2008). This paper examines Carrells et al’s research along with three other research articles to review how DNA is collected, the effects that is has on a juror and the pros and cons of DNA collection in the Forensic Science and Criminal Justice community.

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.

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.

DNA is one of the most important pieces of evidence that a criminal justice agent can use in a court of law. There ae slim to no crimes committed that doesn’t have some type of DNA evidence left behind. Some DNA evidence could be, but not limited to, fingerprints, blood, hair, and any other bodily fluids. DNA is known as Deoxyribonucleic Acid, and is one of two types of molecules that encode genetic information (Medicine.net, 2017). DNA is characteristically unique to each person individually, unless they are a twin. DNA dictates a person’s look such as their eye color, blood type, height, hair color, skin color, etc. With this genetic information, intense testing can be done to find who may be connected to the genetic makeup of each stand

Restriction Enzyme Digestion – The experiment was begun after putting on gloves to avoid any chemical contact with the skin. Four microtest tubes were obtained, and each of them was labeled to contain the different enzymes or suspect DNA. Two of the microtest tubes were used for suspect one and the two different restriction enzymes, while two other microtest tubes were labeled for suspect two and the two restriction enzymes. After labeling the tubes, the contents that were at the bottom were taken out by slightly tapping them. Then to begin setting up the enzyme reactions, a micropipette was used to obtain 10 μL of the reaction buffer which was added to each of the four test tubes. The buffer is important because it carries the electrical current from the power supply in the gel. After the reaction buffer was in each, the microtest tubes were individually filled with their specific enzymes and DNA, shown in summary through Table 1.1 below. The restriction enzymes are used to cleave the DNA at specific

In order to extract DNA from any living thing, we needed to first gather the materials. Then we began the experiment. Step 1, put in a blender 1/2 cup of split peas (100ml), 1/8 teaspoon table salt (less than 1ml), and 1 cup cold water (200ml). Next, we blended the materials on high for 15 seconds. This allowed the pea cells to separate from each other, so we now had a really thin pea-cell soup. Step 2, poured our thin pea-cell soup through a strainer into another container. Added 2 tablespoons of liquid detergent (about 30ml) and swirled to mix. We then let the mixture incubate for 7 minutes. Poured the mixture into test tubes containers, and filled each about 1/3 full. Step 3, added a pinch of meat tenderizer to each test tube and stirred gently to make sure we didn’t break up the DNA. Step 4, tilted our test tube and slowly poured rubbing alcohol (70-95% isopropyl or ethyl alcohol) into the tube down the side so that it forms a layer on top of the pea mixture. Poured until we had about the same amount of alcohol in the tube as pea mixture. Alcohol is less dense than water, so it floats on top. From there we looked for clumps of white stringy stuff where the water and alcohol layers meet. The white stringy stuff was tangled DNA molecules. Thus, we completed DNA extraction. As we performed the experiment we made no changes to the original protocol.

Advances in DNA technology has expanded greatly in the world of forensic science. In the past a vast number of crime scene evidence was not considered for analysis is now being tested. Trace DNA is more effective in this century when convicting a criminal than it was 20-30 years ago. Due to the consist improvement of DNA technology forensic scientist are able to put away criminals the correct way.

There were several steps used to acquire the colony necessary for the PCR. First a student forearm was swabbed using a cotton swab, the cells were then placed in an agar plate. DNA was then extracted from the cultured bacteria by using a technique to lyse the cells and solubilize the DNA, then enzymes were used to remove contaminating proteins. The DNA extraction consisted of a lysis buffer that contained high concentrations of salt for denaturing. Binding with the use of ethanol and a washing step to purify the DNA. The final step for the DNA extraction was elution where the pure DNA was release. Proceeding the extraction of DNA the results of the 16s gene amplification were examined through gel electrophoresis it was analyzed by estimating the size of the PCR bands with marker bands. After measuring the success of the extraction, a technique called TA cloning was started. Cloning of PCR products was done by using partially purified amplified products with

What is DNA? The scientific definition is “deoxyribonucleic acid, the biological polymer that stores the genetic information in all free living organisms. Two linear molecules entwine to form the double helix. Now that the definition has been stated, let’s now define what DNA means to a crime scene or case investigator. In the law enforcement business DNA has been introduce as a revolutionary and efficient accurate tool to solve and crack modern and cold cases. It also has played major roles in courtrooms through out the nation on either proven guilt, or revealing the truth behind the innocence on the wrongly accused and convicted by our own court system. DNA has also brought justice to

Restriction enzymes cut DNA at certain sites to create multiple DNA fragments. Restriction enzyme HindIII has known DNA fragment lengths and recognition sites when digesting lambda DNA, while the lambda DNA recognition site for restriction enzyme XhoI is unknown. The goal of this study is to determine the lambda recognition site of XhoI by comparing a HindIII digest and a HindIII and XhoI double digest on an electrophoresis gel. The HindIII digest had a band at 9.4 kb, but this band was not visible in the double digest, therefore we concluded the recognition site for XhoI was around 9.4kb. There were also two additional DNA

Analysis of DNA from practicals 1 and 2 using the technique of agarose gel electrophoresis and analysis of transfomed E. coli from practical 2 (part B)

What is DNA? Is it these winding strands that look like ladders or is it what gives a person blonde hair and blue eyes? Actually, DNA is both of these things. DNA is a person’s genetic makeup–their hereditary blueprint passed on by their parents. It is a part of almost every cell in the human body. In each cell, a person’s DNA is the same; it stays the same throughout their lifetime. DNA is found in skin tissue, sweat, bone, the root and shaft of hair, earwax, mucus, urine, semen, and vaginal or rectal cells. The DNA found in a person’s saliva is the same as the DNA found in their blood. Parts of the DNA determine our physical characteristics, such as eye and hair color, height, and bone structure, but the

After the incubation, 1.5 mL of each of the three cultures were added to eppendorf tubes and centrifuged at 13,200 rpm for 1 minute. An alkaline lysis procedure like that of Birnboim and Doly was then performed to extract the plasmid DNA with 200 μl of alkaline SDS detergent solution (Birnboim & Doly, 1979). After

DNA is deoxyribonucleic acid, which is found in almost all living things. DNA serves as a code for the creation and maintenance of new cells within an organism. Within humans, it is found in almost every cell. Although most of our DNA is found within the nucleus of our cells as nuclear DNA, a very small amount of our DNA is also found within the mitochondria as mitochondrial DNA. Because mitochondrial DNA is generally not used for solving crimes, for the purpose of this paper it will be disregarded.

Due to the DNA’s specificity, samples can be utilised for identification. DNA is a nucleic acid composed of deoxyribose sugar bound to a phosphate group and one of four nitrogenous bases (adenine, guanine, cytosine and thymine). Each section of these three components are referred to as nucleotides, which are joined to the phosphate or sugar of another nucleotide by strong covalent bonds to form a backbone. The nitrogenous bases are joined to complimentary bases of another nucleotide (adenine with thymine, guanine with cytosine) to create a double stranded molecule (Figure 2). To complete the double helical structure, the molecule coils to compact it’s contents. DNA molecules can contain up to two million base pairs, with a human genome containing approximately 3 million base pairs. The random assortment of nitrogenous bases as well as the numerous mutations within certain DNA sequences, results in genetically diverese DNA molecules and genomes between individials.