What is 'gel electrophoresis,' and why is it...

[cardin2287]

...so important for DNA testing in criminal cases?

[Ponokahontas]

It's a process where DNA is moved and separated by electrical currents bands are formed on a gel called agarose. It shows similarities and differences between relations and non relatives. The gel created is unique to you and therefore is how DNA testing can tell if the DNA supplied came from a certain source

[spaharionline]

Gel electrophoresis is a method that separates macromolecules-either nucleic acids or proteins-on the basis of size, electric charge, and other physical properties.
A gel is a colloid in a solid form. The term electrophoresis describes the migration of charged particle under the influence of an electric field. Electro refers to the energy of electricity. Phoresis, from the Greek verb phoros, means "to carry across." Thus, gel electrophoresis refers to the technique in which molecules are forced across a span of gel, motivated by an electrical current. Activated electrodes at either end of the gel provide the driving force. A molecule's properties determine how rapidly an electric field can move the molecule through a gelatinous medium.

Many important biological molecules such as amino acids, peptides, proteins, nucleotides, and nucleic acids, posses ionisable groups and, therefore, at any given pH, exist in solution as electically charged species either as cations (+) or anions (-). Depending on the nature of the net charge, the charged particles will migrate either to the cathode or to the anode.

[ME_TJ]

Each nucleotide is a piece of DNA carries a phosphate group which is negatively charged.Thus differet lengths of DNA gives different total charges. These differences can be used to seperate pieces of DNA of different lengths by placing them in an electrical field and allowing them to migrate to the positive electrode. This is done in a gel and is known as 'gel electrophoresis'. The gel is made up of Agarose.

THis is one of the steps in DNA fingerprinting. Here the sample form the scene of crime is compared with that of person to identify the criminal.
A DNA fingerprint is obtained by a series of steps. One of the steps is gel electr5ophoresis.

[omic]

DNA of every individual contain unique number of satellite sequences, which is tandem repeat of DNA. This is important in criminal cases when blood, or other body fluids is found and subsequently compare with suspected people.