The experiments covered in this report are based on the topic of DNA polymorphisms, these according to Houseman (1995) are differences in the DNA that occur between individuals. The polymorphisms under investigation here are classified as VNTR’s (variable number tandem repeats) and RFLP’s (restriction fragment length polymorphism). The first experiment is concerned with DNA polymorphisms that are known as VNTR’s, sections of DNA which have repeated nucleotide base sections in which the repeats vary in number per individual, here the VNTR’s chosen were D1S80 and D3S1358. The second centred on Restriction Fragment Length Polymorphism (RFLP) analysis and how the technique lends itself to the identification of genetic diseases. Each experiment
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As DNA is a negatively charged molecule the samples when run through the gel move towards the positive end of the gel, this is important to remember during the setup of the gel so that the electrodes are placed correctly. For each region of DNA under investigation the size of the molecule depends on the amount of nucleotides within that sequence, for the first experiment this is the number of repeats the molecule has and for the second experiment this is how and where the DNA section has been cut. The bigger the section of DNA amplified by PCR the smaller the distance travelled on the gel, comparing the distance travelled of the sample in question to a known sample (called a ladder) is how the size of the sample is found. Holmes, Jones, Reed and Weyers (2013) state that gels can be run vertically and horizontally and varying types of supporting media can also be used, both of these are demonstrated throughout the practical sessions. The first practical used the combination of a vertical gel and polyacrylamide media, this is known as polyacrylamide gel electrophoresis (PAGE) and has a key role in protein analysis. Both D1S80 and D3S1358 have been shown in numerous papers, with the papers by Limborska et al (2011) and Momhinweg et al (1998) showing particular correlation to the first experiment undertook by the group. The papers show how these non-coding regions of DNA can be a useful tool in both evolutionary and population genetics, allowing scientists to predict the heritage of an individual based on the number of repeats that individual has and comparing that to other individuals in that
As DNA is a negatively charged molecule the samples when run through the gel move towards the positive end of the gel, this is important to remember during the setup of the gel so that the electrodes are placed correctly. For each region of DNA under investigation the size of the molecule depends on the amount of nucleotides within that sequence, for the first experiment this is the number of repeats the molecule has and for the second experiment this is how and where the DNA section has been cut. The bigger the section of DNA amplified by PCR the smaller the distance travelled on the gel, comparing the distance travelled of the sample in question to a known sample (called a ladder) is how the size of the sample is found. Holmes, Jones, Reed and Weyers (2013) state that gels can be run vertically and horizontally and varying types of supporting media can also be used, both of these are demonstrated throughout the practical sessions. The first practical used the combination of a vertical gel and polyacrylamide media, this is known as polyacrylamide gel electrophoresis (PAGE) and has a key role in protein analysis. Both D1S80 and D3S1358 have been shown in numerous papers, with the papers by Limborska et al (2011) and Momhinweg et al (1998) showing particular correlation to the first experiment undertook by the group. The papers show how these non-coding regions of DNA can be a useful tool in both evolutionary and population genetics, allowing scientists to predict the heritage of an individual based on the number of repeats that individual has and comparing that to other individuals in that