DNA Fingerprinting
DNA is found in almost every cell in the human body. Skin, hair follicles, semen, saliva, and blood are common sources of crime-scene DNA. The DNA figure is known as a double helix which is structured by four base pairs: A,C,G,and T. Genome in DNA makes up the millions of these four base pairs. These codes manufacture different proteins which each carry out different functions for the body to do. (C.11)
What is DNA?


DNA fingerprinting allows scientists to compare collected DNA from a crime scene with a sample collected from a suspect. Gel electrophoresis separates proteins in the DNA so the scientists can compare different obtained DNA samples. The machine creates segments that can help distinguish relations between the different DNA samples. Each piece is labeled for a different sample taken from a suspect. Every DNA sample was saved into a database that can see previous crimes someone has committed.DNA fingerprinting is used to find diagnosed inherited disorders that are common between the child and parents. Segments created from gel electrophoresis (below) shows the same traits between the child and parents. (C.35)
Click here to lean more on gel electrophoresis.
Above is an image of a double helix (I.8)


DNA fingerprinting created by gel electrophoresis. (I.37)


Above are the steps to gel electrophroesis(I.9)
Below are the 3 basic types of fingerprints (I.10)


Fingerprinting
The most commonly type of DNA fingerprinting is fingerprinting. Fingerprinting is used to compare traces of fingerprints from fingers left behind. No two fingerprints are the exact same. Twins even have different ridges on their fingertips. There are three common fingerprints which include: loops, whorls, and arches. Fingerprint powders are used to make fingerprints at a crime scene visible. The forensic scientist then takes special clear duct tape and transfers the fingerprint from the object to this tape so it can then be ran through a machine and analyzed further. Fingerprinting, probably one of the easiest methods used has caught thousands of criminals throughout time. (C.12)

Can fingerprints change?
​The answer to this in NO! A scratch, scrape, or burn to someone's finger cannot and will not affect the structure of the ridges on their fingerprint. The skin is layered and will eventually regrow. The only way to damage a fingerprint is by destroying papillae. Papillae are small projections that connect inner skin and the ridges of the fingerprint. Law enforcement officials worry that criminals will eventually discover that there is no way to tamper with their fingerprint This may lead to incidents of criminals cutting off innocent citizens fingers in order to commit a crime and not lead evidence of them behind. In a past case several robbers of Malaysia cut off an innocent man's finger and used it to steal his Mercedes. Do not worry though! Several companies are inventing new scanners that detect blood flow so they know if the finger is steal alive. (C.28)
Snps
Forensics also use a system called SNPs when dealing with DNA. SNPs, abbreviated for single nucleotide polymorphism and pronounced "snips", are the most common type of genetic variation among people. They can act as biological markers, helping scientists locate specific genes that cause problems. SNPs are mistakes in a genome made up of the four base pairs SNPs do not always occur but when they do it happens during replication of a DNA. The mutations include: a deleted pair, extra pair, or change of a base pair when copied. If two different samples are collected SNPs can be used to detect if both samples have the same mistake in their genome. This method is new and is easier for forensics to use. SNPs are the mutations, or defects located in a gene. NO NEED TO WORRY because most SNPs have no effect on health or development of the human body. SNPs provides criminalists with a faster way of comparing DNA results found. (C.33)
Breaking down SNPs (V.5)