DNA Fingerprinting.

Authors Avatar

DNA Fingerprinting

        This is a way of making a pattern from pieces of DNA cut with restriction enzymes.  Everybody has a different DNA, so the pattern or fingerprint is unique to each individual.

        DNA is a long chain, double-helix molecule composed of building units called nucleotides. Each nucleotide consists of a sugar, a phosphate and a nitrogenous base. There are four types of nitrogenous base: adenine, guanine, cytosine and thymine. The genetic information carried by a DNA molecule is contained in the sequence of these four bases. A gene is a length of DNA that codes for a specific protein or polypeptide. They are organised into chromosomes and located within the nucleus in human cells. Only 2% of the DNA of a human cell contains genes. The rest consists of non-coding sequences of bases called introns, which occur between or within a gene. Introns can be between 60 and 100 000 bases long. A single gene can contain 50 introns between exons (coding parts of the DNA molecule). The function of introns is unknown.

Join now!

        Within non coding regions between genes there are short sequences of bases called core sequences that repeat themselves over and over again, sometimes up to 100 times. These repeated regions of DNA are called mini-satellites or variable number tandem repeats. Different people have different numbers of repeated core sequences; therefore they have different sized mini-satellites. The greater the number of repeats the longer the mini-satellite.

        DNA fingerprinting is based on two observations. Firstly, the number of repeats of a core sequence tends to vary considerably from person to person. Secondly, each individual has 50-100 different types of ...

This is a preview of the whole essay