Science

947 Words4 Pages
DNA Technology Task 3 – Poster DNA fingerprinting, also known as DNA profiling, is a technique used in forensic science that identifies individuals based on various characteristics of their DNA. Although the DNA sequences between humans are 99.9% identical, DNA fingerprinting is able to distinguish between individuals due to the presence of specific sequences within the non-coding region of the genome known as satellite DNA. This satellite DNA consists of long stretches of DNA made up of repeating base sequences known as short tandem repeats (STR). These STRs considerably vary in length between individuals, particularly between unrelated individuals, allowing exact individuals to be identified. One major use of DNA fingerprinting is in…show more content…
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
Open Document