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Poly-A Tail

Definition

The Poly-A tail is a string of adenine nucleotides added to the 3' end of a pre-mRNA molecule during RNA processing.

Analogy

Think of the Poly-A tail as the knot at the end of a balloon. It helps keep everything inside (the mRNA) from escaping and getting lost in translation, just like how a knot keeps air inside a balloon.

Related terms

Adenine: One of the four main bases found in DNA and RNA. It pairs with thymine in DNA and uracil in RNA.

mRNA (Messenger RNA): A type of RNA that carries genetic information from DNA to ribosomes where it specifies the amino acid sequence for protein synthesis.

RNA Processing: The modifications that a primary RNA transcript undergoes to become mature mRNA. These processes include splicing, 5' capping, and addition of a poly-A tail.

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AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.