Rna Polymerases - Research Article from Macmillan Science Library: Genetics

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Types of Polymerases

Prokaryotic organisms (Eubacteria and Archaea) have only one type of RNA polymerase. Eukaryotic organisms (animals, plants, fungi, and protists) have three types, called pol I, II, and III, and each transcribes a different set of genes. Pol I synthesizes RNA for the large subunit of the ribosome (the protein-making machinery of the cell), and one piece of RNA for the small subunit. Pol II creates messenger RNAs, which provide a template for protein synthesis. Pol II also creates numerous small nuclear RNAs (snRNAs), which modify RNAs after they are formed. Pol III synthesizes transfer RNAs (tRNAs), the RNA for the small subunit of the ribosome, and other snRNAs.

The three eukaryotic polymerases can be distinguished in the laboratory by the degree to which they are inhibited by the alpha-amanitin poison from the mushroom Amanita phalloides. Pol I is completely resistant to its effects, pol III...

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This section contains 796 words
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Macmillan Science Library: Genetics
Rna Polymerases from Macmillan Science Library: Genetics. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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