Tandem Repeats Essay

(PCR), which isolates small fragments of DNA that have a high degree of variability from

Basically, our DNA (deoxyribonucleic acid) is our genes, and every person, except for twins, are born with a different DNA profile and that is in a giant database, containing every DNA profile of every person in the world. DNA testing started in 1985 by scientist Alec Jeffreys and was first used to solve a crime a year later. Before 1985 DNA evidence could not be used in court because it wasn’t invented yet, this increased the number of wrongful convictions which would have been prevented using DNA analysis. However, DNA analysis can still be used to solve crimes that occurred prior to the invention of DNA analysis, with a sufficient amount of DNA to be analyzed of course, which is a very small amount. Only a small amount of DNA is needed to find out who it belongs to, it can be found in blood, saliva, finger residue, hair, skin, semen and more.

exception of identical twins, DNA fingerprinting is a reliable method used to determine the parents of a given baby. DNA fingerprints can be derived from restriction

DNA Profiling exists in blood, bone, hair follicles, saliva, semen, skin and sweat. They are the same in every cell and retain their distinctiveness throughout an individual’s lifetime.

We were using a restrictive enzyme to cut the DNA into smaller fragments. For the restriction digest we pipet 4 micrometers of enzyme mix into the bottom of each of our colored tubes making sure to use a new tip for each sample. Next, we capped the tubes and mixed the contents by flicking the tube a little bit with our fingers. After we mixed the contents, we tapped the tube to make sure all the liquid would go to the bottom of the tube. Then, we put the colored tubes in the heating blocks and we let them incubate for 35 minutes at 37 degrees Celsius.

DNA analysis is a forensic tool that allows a suspect to be linked to a crime scene. Using the DNA analysis method, requires law enforcement officers to obtain DNA from the suspect and compare the suspects DNA,

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.

There are many sources of DNA for testing. Blood is one of the key sources, though the surface on which a bloodstain is found can profoundly affect the ability to successfully perform an analysis. In addition, bloodstains may be mixtures of blood from two different people and can produce DNA profiles that are more complex than those from a single individual. Ironically, DNA profiling may be the only way to determine if a given stain is a mixture. Semen stains are the most common evidence to be submitted for DNA analysis, which is not surprising since the cases in which DNA testing has been used the most often are rapes. DNA can also be extracted from tissues (taken at autopsy), hair roots, saliva, and in rare instances, urine.(4) It is important to note that only a miniscule amount of DNA is needed for analysis. For example, the amount of DNA found at the root of one hair is usually sufficient. Environmental factors also play a role in determining whether a particular sample of DNA can be utilized. Moisture, sunlight, bacterial action and heat are detrimental to the DNA. Depending on the intensity and combination of these conditions, survival of the DNA is measured in weeks or months. Even so, DNA in usable amounts can

The marker DNA contained DNA fragments whose base pairs and size were previously known. Thus, when it is separated through gel electrophoresis, the strands visible can be compared to the other DNA strands and the size of the adjacent strands can be estimated. A semi-log graph was utilized to determine the unknown DNA fragment sizes. The distances migrated, and the DNA fragment size of the marker DNA was first plotted. Then, a line of best fit was drawn for reference. The distance the DNA fragments of crime scene DNA, suspect one’s DNA, and suspect two’s DNA had traveled through the agarose gel was calculated. Once those values were known, the points along the line of best fit that were intersected by the x-axis values of the distance traveled by the DNA fragments were the estimated sizes of the separated DNA fragments. Once the sizes were discovered, the data was observed in order to exonerate and implicate a suspect. After observation, suspect one was exonerated as suspect two’s DNA fragments closely resembled and matched up with those in the crime scene

Forensic DNA analysis is still a relatively new method that has been used to solve cases such as crimes and paternity tests. This method of forensic evaluation is examined by using genetic material, DNA, an acronym for deoxyribonucleic acid. Although each individual’s DNA differs from someone else’s, with the exception of identical twins, around 99.9% of DNA is the same in each person ("The FBI DNA Laboratory"). Therefore, in order to identify the genetic profile of the individual being analyzed, scientists focus on the remaining 0.1% of DNA that differentiates one person from another ("The FBI DNA Laboratory").

Due to the presence of negatively charged phosphate groups within the sugar-phosphate backbone of DNA, the DNA fragments diffuse through the gel towards the anode. The smaller fragments are more able to penetrate through the gel and thus travel the furthest whereas the larger fragments travel a shorter distance. The exact size in bases for each separated fragment in a given sample of DNA can be determined by comparing each fragment against standard fragments of known length. This is commonly known as a ladder within the laboratory. For the purposes of a crime scene investigation, multiple DNA samples would be simultaneously run through the gel, Once separated, a DNA fragmentation pattern is produced that allows the criminal to be identified. As shown in the figure below, a DNA sample obtained from the crime scene is compared to two possible suspects. The pattern of suspect 1 more closely matches the pattern of the DNA obtained from the crime scene thus allowing the true criminal to be correctly identified. Similarly, for paternal testing, the DNA samples of the mother and child are compared to the potential fathers. The fragmentation pattern of the child should resemble both the mother and true father as half of child’s alleles are inherited from the mother and father. Male 1 resembled the child’s

Like in any biological field we used a Polymerase Chain Reaction (or PCR for short), which is used to amplify “specific DNA

As observed, several protocols are used for DNA extraction and analysis, and there is no standard methodology. Therefore, researchers must carefully evaluate the conditions of the material to be examined, especially when dealing with forensic cases, in which there is a greater risk of sample contamination and influence of environmental factors, in addition to a small amount of material available in most situations. The PCR technique has

DNA is a double helix molecule that contains information that is used to make up a person’s body. DNA controls every aspect of a person’s body from their eye and hair color, height, and other features. DNA’s specific and unique characteristic can be crucial when solving a crime. DNA can be used to convict a suspect or exonerate an innocent person. When DNA is found it is even more important that is handle properly to ensure proper identification and accuracy of testing. The evolution of DNA technology is vital to the process of solving crimes, however the process by which DNA is found and handle can jeopardize its powerfulness.

In order to create a DNA fingerprint, a sample of cells containing DNA must be obtained first. This may be in the form of hair, blood, or skin. DNA is extracted and purified from the cells. This was originally done with restriction fragment length polymorphic technology. During this procedure, DNA is broken down into individual strands at specific locations. These strands, known as restriction enzymes,