BIOL 200

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Tiye
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172614
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BIOL 200
Updated:
2012-09-22 22:11:43
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Lecture
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4th Lecture
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  1. Ingredients needed for transcription in bacteria
    • DNA template: to serve as a blueprint for the RNA sequence 
    • Ribonucleotides: to serve as a monomers for RNA polymerization 
    • RNA Polymerase: catalyses synthesis of RNA
  2. Naming of parts
    • Promoter: extremely important for the recognition of the RNA 
    • +1 site: site is sort of what is called the start of the transcription
    • Coding sequence: region of gene that codes for the protein
  3. sense strand vs anti-sense strand 
    sense strand is the nontemplate strand, the anti-sense strand is the template strand 
  4. Initiation of transcription in prokaryotes 
    1. Polymerase binds to promoter sequence in duplex DNA. "closed complex"

    2. Polymerase melts duplex DNA near transcription start sit, forming a transcription bubble. "Open complex"

    3.Polymerase catalyzes phosphodiester linkage of two initial rNTPs 
  5. Elongation in Prokaryotes 
    Polymerase advances 3'to5' down template strand, melting duplex DNA and adding rNTPs to growing RNA

    During transcription we transiantly produce a funky hybrid of DNA and RNA
  6. Formation of phosphodiester bond
    Polymerization involves the formation of a phosphodiester linkage between the free 3' hydroxyl of the growing RNA chain and the alpha phosphate group of the incoming rNTP
  7. Termination
    At transcription stop site, polymerase releases completed RNA and dissociates from DNA 
  8. Holoenzyme?
    Holoenzyme scans along the DNA until it encounters a promoter region to bind to and form a closed complex.

    Consist of core enzyme and sigma actor. 
  9. Task of sigma factor
    • Found in the Holoenzyme
    • Its task is to find the promoter
    • "find where the gene is"
  10. Alpha subunit and Beta subunit are important in terms of....
    They are important in terms of catalysis
  11. Omega does what?
    Is there for stabilizing 
  12. Why is B' (beta prime) important 
    Important to grab DNA onto the template
  13. How does the Sigma (σ) factorrecognize the promoter region?
    by binding to specific sequence motifs, which areessential for promoter activity (the -10 and -35 regions)
  14. Translation 
    Process in which messanger RNA is translated into proteins
  15. Three roles of RNA
    mRNA: Genetic information DNA in form of codons 

    tRNA: key to decipher the codons in mRNA. Each tRNA has an associated amino acid and anticodon 

    rRNA: associates with proteins to form ribosomes
  16. What is never translated?
    tRNA and rRNA, there functional identity is to transcript
  17. Prokaryotes subunits are made of what?
    rRNA and proteins
  18. Initiation of Prokaryotic translation
    • Initiation Factors (IFs) associate with the 30S subunit forming the preinitiation complex  
    • IF1 and IF3 assists the loading of mRNA and the initiation aminoacyl-tRNAforming the 30S initiation complex which binds the transcript at the initiationcodon, AUG
    • IF1 and IF2-GTP facilitate theloading of the 50S subunit forming the 70S initiation complex
  19. Elongation in Prokaryotic translation
    • Elongation Factors (EFs) arerequired for the stepwise additionof amino acids
    • It’s a ribozyme - the 23S rRNA -that carries out thepeptidyltransferase reaction
  20. Termination in Prokaryotic translation
    • When the mRNA ribosome-tRNA-peptidyl complex reaches a stopcodon, Release Factors(RFs) mediate thetermination of proteinsynthesis.
    • RF1 and 2 mimic tRNA
    • RF3-GTP catalyzes the cleavage of the peptidyl tRNA releasing the protein chain
  21. When can you start translation 
    Not until those tRNA molecules are coupled with their bonded amino acids forming an Amimoacyl-tRNA
  22. Wobble base pair in the first, or wobble position of anticodon
  23. Wobble base pairs in third or wobble, position of codon of an mRNA

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