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Exploring RNA Structure and Transcription: A Comprehensive Overview

Delve into the world of RNA, from its structure and types (mRNA, tRNA, rRNA) to the intricate process of transcription. Understand the genetic code, codons, and the stages of transcription – initiation, elongation, and termination. Learn how RNA differs from DNA and plays a crucial role in protein synthesis.

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Exploring RNA Structure and Transcription: A Comprehensive Overview

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  1. RNA Structure and Transcription Joyce Fiel Matt Speir Alliver Verzon Shann Bunggay

  2. Overview • RNA Structure • Types of RNA • mRNA • tRNA • rRNA • The Genetic Code [Codons] • Transcription • Initiation • Elongation • Termination

  3. What is RNA? • RNA = Ribo Nucleic Acid • Single Strand • Similar to DNA but pyrimidyne base, uracil replaces thymine and ribose replace deoxyribose • Five-carbon sugar • Nucleotides: Guanine, Cytosine, Adenine, Uracil • Backbone made of alternating ribose and phosphate groups • Other bases: thymine, pseudouridine and methylated cytosine and guanine.

  4. Types of RNAMessenger RNA (mRNA) • Transcribed from DNA template • Carries coding information to ribesome (site of protein synthesis) • Moves DNA information to translation machinery • Always has 5’ cap between two modified nucleotides • Most have poly-Adenosine tail at 3’ end • Provides templates used to make amino acids

  5. Types of RNATransfer RNA (tRNA) • Short RNA molecule • also called anticodon or adaptor molecule.  • One or more tRNAs for each amino acid • 3’ end of tRNA attaches to amino acid • Decodes information in DNA • More than 20 different tRNA molecules • Each have between 75-95 nucleotides • 4 arms, 3 loops

  6. Types of RNARibosomal RNA (rRNA) • Most abundant – 80% of RNA • Building blocks of ribosomes • Combines with proteins from cytoplasm to make ribosomal subunits • 3’ end attaches to an amino acid • Several roles in protein synthesis • Catalytic role • Recognition role • Structural role

  7. Dictionary of the Genetic Code

  8. Transcription http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.html

  9. Transcription Animation http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.html

  10. What is Transcription? • first step in protein synthesis • DNA-directed synthesis of RNA • Utilizes enzyme called RNA Polymerase • Takes place in 3 stages • Initiation • Elongation • Termination

  11. Stage I:Initiation and RNA Polymerase Binding • Takes place in promoterregion of DNA • RNA polymerase attaches, transcription initiated • DNA unzips • Binding polymerase is different between prokaryotes and eukaryotes • Transcription factorsrequired • Results in transcription initiation complex • TATA box :crucial promoter DNA sequence

  12. Stage II: Elongation of the RNA Strand • DNA continues to unwind • Takes place in coding region of DNA • 10-20 DNA bases exposed to pair with RNA nucleotides • Enzyme adds nucleotides to 3’ end of RNA molecule • DNA double helix reforms, RNA peels away • Transcription in eukaryotes- 60 nucleotides per second • Multiple RNA polymerase can transcribe a single gene simultaneously

  13. Stage III: Termination of Transcription • Transcription stops when RNA hits the terminator DNA sequence • RNA sequence makes actual termination signal (stop codon) • In prokaryotes: transcriptions stops at end of termination signal • In eukaryotes: mRNA is cut free from enzyme about 10-35 nucleotides after termination signal (AAUAAA sequence in pre-mRNA)

  14. Works Cited • http://cnx.org/content/m11416/latest/transcription_initiation.jpg • http://tigger.uic.edu/classes/phys/phys461/phys450/ANJUM04/RNA_sstrand.jpg • http://academic.brooklyn.cuny.edu/biology/bio4fv/page/antico.htm • http://www.ndsu.edu/instruct/mcclean/plsc731/transcript/transcript1.htm • http://www.johnkyrk.com/DNAtranscription.html • Trusty Bio book • Cliffnotes

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