alu sequence family

alu sequence family

A family of DNA sequences in the human genome, some 300 base pairs long, that serves no apparent genetic purpose. The alu sequences are found scattered throughout the chromosomes and occur about 500,000 times, constituting about 5 per cent of human DNA. Copies of the alu sequences occur in slightly varying forms and these variations allow DNA FINGERPRINTING of individuals. Alu sequences are mainly of cytosine/guanine and are specific to species and do not code for any product. They cause visible gram-negative bands when chromosomes are stained with Gram's stain and can be used to identify human DNA for forensic purposes.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005