DNA Analysis
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Introduction
One of the most efficient modern technologies used in criminology to deter crime and identify the biological father to a child is DNA fingerprinting[1]. Most countries are equipped with databases with high degree of complexity that stores their citizen’s genotype data. DNA fingerprinting technology has evolved from simple techniques that were mostly physical and operated by hands to sophisticated biobanking and analytical chemistry. The advanced technology obtains fingerprints from a DNA region in an individual by closely following the polymerase chain reactions. Although 99% of DNA from unrelated people is the same, the 1% difference in DNA in some regions provides the necessary information in determining the biological father to a child, diagnoses of hereditary conditions and in criminology to reduce crime. The difference in DNA compositions between two people is classified into three categories. These categories are the Short Tandem Repeats (STR), Single Nucleotides Polymorphism (SNP) and the Variable Number of Tandem Repeats (VNTR)[2].
Method
In this study, the samples comprised of cells that were peeled off my cheek using saline mouthwash and a brush that is designed for this particular purpose. The samples were placed in a resin known as Chelex that was bonded to cations (metal ions)[3]. It is possible to break down DNA using the metal ions at elevated temperatures. The process stops PCR reaction from taking place. In order to get lid of cell debris, the samples were placed in boiling water for dissolution to take place followed by centrifugation process.
PCR reaction at this stage involved chromosomal DNA in supernatant cells. The reaction involves Taqpolymerase that is hard to destroy through heating, strands of nucleic acid that are used as starting point for DNA analysis known as primers, deoxynucleotide building blocks contained in DNA and a buffer solution containing magnesium chloride salt all mixed together[4]. The mixture is put in a DNA amplifier where it is passed through thirty-five cycles. In this study, the D1S80 region obtained by the thermal cycler was studied using motion of dispersed agarose gel, a process known as electrophoresis.
The PCR strands of nucleic acid isolate the D1S80 region and identify the area where chromosome 1 is located. The amplification of the chromosome leads to separation of DNA in order of the size using the dispersed particles of agarose gel (electrophoresis). In order to improve the visibility of the bands ethidium bromide is applied on the separated DNA a process known as staining, which makes one or two bands to be visible. The results of this study showed that for the D1S80 locus, one could be either heterozygous or homozygous. Many alleles were recognizably different as clear bands made of millions of similar alleles. The location of the band on the gel is correlated with the size of a D1S80 allele, which equals the number of repeat units. It was proved that the distance moved by the alleles is inversely proportional to their sizes.
Approximately three out of four of individuals are heterozygous at the D1S80 LOCUS. Compare the class data with the general population
There exist two D1S80 alleles passed on from the biological mother and father. The variation of VNTR passed on from parents is responsible for the ¾ heterozygous at D1S80 of any given population. However, the electrophoresis for the class indicates about 45% heterozygous population at D1S80. This class value is less than the expected due to errors such as contamination and technical faults.
State the patterns of the D1S80 primers and the matching genome locations at which they anneal by clearly indicating the sequences and their 5 and 3 ends
Sequence for the forward strand
5’ GAAACTGGCCTCCAAACACTGCCCGCCG 3’
Pattern 3’ CTTTGACCGGAGGTTTGTGACGGGCGGC 5’
Sequence for the reverse strand
5’ GTTCCCCGTGCACGTAGAGGTTGTTCTG 3’
Pattern 5’ CAAGGGGCACGTGCATCTCCAACAAGAC 3’
Basing on the concentration of DNA values in the samples generated through UV absorbance and the SYBR green techniques provide a brief comment. State the more accurate value
SYBR green technique has a higher accuracy compared to UV absorbance because the former technique binds for double primer DNA as opposed to single primer DNA. Nevertheless, the UV absorbance efficiently responds for any nucleotide molecules as opposed to SYBR green technique, which is limited to double primer DNA.
Some DNA samples were store at 95 degrees Celsius, then suddenly chilled or cooled gradually. Comment on their values. Where higher hybridization would be recorded?
Hybridization refers to the linking of complimentary ssDNA to form dsDNA in annealing space. Hybridization is greater in gradually cooled DNA cells compared to the suddenly cooled ones because of the extended time during the gradual cooling that enhances linking of ssDNA to form dsDNA and increases concentration.