What Chemical Can Change DNA Structure or Color?

This thymine molecule is one type of base pair found within the DNA molecule.

Ethidium bromide is a dark red crystalline compound that is also a fluorescent dye used to change the color of DNA by bonding within its structure. A common laboratory chemical, ethidium bromide must be handled with care as it's toxic and a potent mutagen.

Description

Ethidium bromide, commonly abbreviated as EtBr, has a chemical structure of 3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide. It is a chemical that fluoresces a reddish-brown color when exposed to ultraviolet light.

Function

Ethidium bromide is used in a lab technique called gel electrophoresis in which DNA fragments are separated on the basis of size in a gel by the application of electricity. Ethidium bromide is used to stain the DNA fragments in order to determine their location within the gel.

Process

Ethidium bromide bonds specifically to the nitrogen portion of the base pairs within DNA molecules. It intercalates within DNA, meaning that it bonds in the spaces between the base pairs. Ethidium bromide also binds to other forms of nucleic acids, such as RNA.

References

• Purdue University: Ethidium Bromide
• Colorado State University: Agarose Gel Electrophoresis of DNA

Resources

• Absolute Astronomy: Ethidium bromide