Primer extension is a technique whereby the 5' ends of RNA or DNA can be mapped.
Primer extension can be used to determine the start site of RNA transcription for a known gene. This technique requires a radiolabelled primer (usually 20 - 50 nucleotides in length) which is complementary to a region near the 3' end of the gene. The primer is allowed to anneal to the RNA and reverse transcriptase is used to synthesize cDNA from the RNA until it reaches the 5' end of the RNA. By running the product on a polyacrylamide gel, it is possible to determine the transcriptional start site, as the length of the sequence on the gel represents the distance from the start site to the radiolabelled primer.
Famous quotes containing the words primer and/or extension:
“Your master Robin Hood lies dead,
Therefore sigh as you sing.
Here lie his primer and his beads,
His bent bow and his arrows keen,
His good sword and his holy cross:”
—Anthony Munday (1553–1633)
“We are now a nation of people in daily contact with strangers. Thanks to mass transportation, school administrators and teachers often live many miles from the neighborhood schoolhouse. They are no longer in daily informal contact with parents, ministers, and other institution leaders . . . [and are] no longer a natural extension of parental authority.”
—James P. Comer (20th century)