MBB 222 Lecture Notes - Lecture 29: Rna Polymerase Iii, Rna Polymerase Ii, Eukaryotic Transcription
20 Dec 2018
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Document Summary
Eukaryotes have three different rna polymerases (rnaps) for synthesis of different. Rna polymerase i (rnap i) in nucleolus synthesizes rrna part of ribosomes. Rna pol ii (rnap ii) in nucleus synthesizes mrna proteins. Rna pol iii (rnap iii) in nucleus synthesizes trna (adaptor for protein synthesis), 5s. Eukaryotic rna polymerase functions were identified by differences in sensitivity to - amanitin. Amanitin is the product of the mushroom amanita phalloides, also known as the death cap . This extremely toxic mushroom destroys the liver and kidney. Amanitin arrests rnap ii during the elongation phase of transcription. Sensitivity to - amanitin can be used to determine which rna polymerase is responsible for transcribing a given rna in vivo. Eukaryotic rna polymerases require transcription factors to bind dna. Eukaryotic rnaps cannot bind dna promoters without the help of other proteins called transcription factors (tfs).
