Bio 201 1st Edition Lecture 35Outline of Last Lecture I. GenesA. George Beadle and Edward TantumII. TranscriptionIII. RNAA. rRNAB. tRNAC. mRNA Outline of Current LectureI. Eukaryotic mRNA processingA. SplicingB. 5’ CappingC. PolydenylationCurrent LectureI. Eukaryotic mRNA ProcessingA. Splicing- Removal of non-expressed introns from transcript prior to translation-Eukaryotic protein-coding genes contain material that’s present in the original transcript, but are removed to make mRNA.-Intervening sequence, intron- sequence that is removed.-Expressed sequence, exon- sequence that encodes protein. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-mRNA and corresponding DNA relationship? 1. Make synthetic RNA probe corresponding to gene. 2. Purify genomic DNA. 3. Boil DNA to denature. 4. Mix with RNA probe. 5. Cool- allowing to hybridize. 6. Electron microscopy. RESULT: RNA binds to DNA in a continuous stretch: rRNA and tRNA, bacterial mRNA, rare “intronless” eukaryotic mRNAS. OR RNA discontinuously binds to DNA. Loops where stretches of DNA do not bind; most eukaryotic mRNAs. B. 5’ Capping- Addition of methyl-guanosine cap to the 5’ end of mRNA. Cap is characteristic of mRNA. 5’ end of all eukaryotic mRNAS have 7 methyl guanosine caps added after transcription. Signals for nuclear export and translation. C. Polydenylation- Addition of a string of adenosines (A) to the 3’ end of mRNA, adds 50-200 A’s to mRNA tail. Signals RNA polymerase to stop. Additional signal for nuclear export. Stability: substrate for exonuclease. This is recognized by ribosome to initiate
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