lecture: transcription and translation

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VASUpharm14
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32990
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lecture: transcription and translation
Updated:
2010-09-06 15:15:05
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im too cool
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IBHS: Skacel part 2 (dos)
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  1. context: RNA
    structure
    • largely single stranded
    • particular shapes: nonconventional vs conventional basepairs due to reactive hydroxyl in 2'C
    • notice:
    • Uracil vs Thymine
    • shapes vs histones
    • nucleus to cytoplasm vs just nucleus
  2. Central dogma of molecular biology
    • replication (DNA to DNA), transcription (DNA to RNA), translation (RNA to PROTEINS)
    • genes can be turned on or off to make different proteins
  3. T/F
    Different genes are made in different amounts
    TRUE

  4. NO PROOFREADING in RNA polymerase, NO PRIMER.
  5. context: Gene structure
    Promotor region
    • 5' untranslated region (5' UTR)
    • initiation site for transcription
    • RNA polymerase BINDING SITE
    • binding site for transcription factors (regulation cis or trans strand)
  6. context: gene structure
    genes
    intron (more: waste) + exons (less: for proteins)
  7. context: transcription
    what polymerase
    • RNA polymerase 2
    • using rNTPs
  8. context: transcription
    Template strand
    strand used as template for mRNA synthesis
  9. context: transcription
    coding strand
    • specifies the sequence of a.a.
    • (genetic code) in future polypeptide
  10. context: types of RNA
    mRNA
    • messenger RNA
    • template for amino acids
    • 3-5% total RNA in cell (really small amounts!!)
  11. context: types of RNA
    t RNA
    • transfer RNA
    • recognize the mRNA with it's anticodon complementary to mRNA codon.
    • to put on corresponding amino acids.
  12. context: types of RNA
    rRNA
    • ribosomal RNA
    • portion of ribosomes
    • hold mRNA to put on tRNA
  13. 4 stages of transcription
    • 1. Initiation (open up helix, needs PROMOTOR to know where to start)
    • 2. elongation (mRNA synthesis 5' to 3', phosphodiester bond)
    • 3. termination (stop signal)
    • 4. post-transcriptional modification (capping, poly A tail, splicing)
  14. context: transcription
    Promotors
    • varying sequences
    • different promotors
    • ex: common ones: -35 and TATA box at -10 based on consensus sequences across a lot of studied subjects.
  15. context: transcription
    bacteria vs eukaryotes
    • 1. 1 RNA polymerase vs 3 RNA polymerase
    • 2. 1 transcription factor vs many general transcription factors (GTFs)
    • 3. no packaging vs packaging (nucleosomes, chromatin)
  16. context: eukaryotic transcription
    promotor region
    upstream TATA box or CAAT box
  17. context: eukaryotic transcription
    enhancer region
    typically upstream of promotor
  18. context: eukaryotic transcription
    transcription factors jobs and kinds
    • 1. transcription factors bind to promotor and recruit RNA polymerase
    • 2. must bind to all promotors to get RNA polymerase = basal transcription factors
  19. context: eukaryotic transcription
    names of transcription factors
    • TFIIx
    • x = b,d,h etc.
  20. context: eukaryotic transcription
    TFIID
    • has a TBP (TATA binding protein)
    • that bends the site to get other transcription factors to bind
  21. context: eukaryotic transcription
    other transcription factors not including TFIID
    positive regulation transcription factors
    • bind enhancer or DNA response elements
    • INCREASE rate of transcription
  22. context: eukaryotic transcription
    other transcription factors not including TFIID
    negative regulation transcription factors
    • bind enhancer or DNA response elements
    • DECREASE rate of transcription
  23. context: eukaryotic transcription
    regulating gene expression
    • Transcriptional activator protein- activate
    • Transcriptional repressor protein -inhibit polymerase activity
  24. BOTTOMLINE:
    gene regulatory proteins
    responsible for controlling gene expression
  25. context: Transcription ELONGATION
    what polymerase?
    RNA polymerase 2
  26. context: transcription Termination
    in Prokaryotes (cause hard to know eukaryotes)
    process to stop sequence
    • 1. Hairpin loop with extensive basepairs formed
    • 2. ADD UUUUU for polymerase comes off
    • 3. RHO protein breaks DNA and RNA apart
  27. context: POST-transcriptional
    3 steps
    • 1) 5' Methylguanosine cap (once 5' is made)
    • 2) 3' poly A tail (protect from endonucleases)
    • 3) splicing out introns (introns removed, exons join, alternative splicing)
  28. context: post-transcriptional modification
    splicing with help
    • with: snRNA, splicesomes (name of splicers in nucleus)
    • 1. 2'OH adenosine forms lariet
    • 2. cleave at exon and intron junction
    • 3. joined exons
    • 4. degrade lariat (introns)
  29. context: post-transcriptional modification
    splicing without help
    • ex: Tetrahymena
    • use ribozymes - RNA catalyze self-splicing
  30. context: post-transcriptional modification
    Bacteria vs Eukaryotes
    • no modification vs modification
    • many proteins vs one protein
  31. context: transcription and translation
    Bacteria vs eukaryotes
    coupled (no nucleus) vs separate (in nucleus then in cytoplasm)
  32. context: translation
    3 components
    • 1. ribosomes
    • 2. mRNA
    • 3. tRNA
  33. Context: translation
    mRNA is translated in what direction?
    protein is synthesized in what direction?
    • 5' to 3' on BOTH!!!
    • amino terminus to carboxy terminus (remember A before C)
  34. context: translation
    peptide bonds synthesize how many NUCLEOTIDES per second
    hint: really fast
    45

    15 amino acids per second. each amino acid has 3 nucleotides in one codon(amino acid)
  35. context: translation
    T/F
    translation is hard and complicated
    • TRUE
    • it takes over 100 proteins to process
    • plus amazing coordination required
  36. 4 steps to TRANSLATION
    • 1. initiation (start- AUG= A Unique Girl -she's one of a kind)
    • 2. elongation (amino acids, peptide bonds)
    • 3. termination (stop codon: UAG- Ur A Girl?, UAA- Ur An Ahole, UGA- U Got Ahole)
    • 4. post-translational modification (cleaving, folding = folded structure) = use RELEASE FACTORS to end everything. REGULATED by the poly A tail.
  37. GENETIC CODE properties (4)
    • 1. one codon = read in triplets (letters)
    • 2. no commas!
    • 3. do not overlap
    • 4. redundant/degenerate - many codons for one amino acid
  38. HOW come 64 codons = only 61 amino acids
    redundancy!
  39. Genetic code
    Alterations (3)
    • 1. silent - no change
    • 2. missense - change amino acid
    • 3. nonsense - stop codon
  40. context: tRNA and translation
    How do you get the amino acid on to the correct tRNA?
    synthetases- enzymes, SPECIFIC for each amino acid
  41. Ribosome binding sites
    • E (exit), P (peptidyl site), A (aminoacyl site)
    • AND mRNA binding site.
  42. context: translation elongation
    polysomes
    MULTIPLE ribosomes translating one mRNA strand
  43. context: post-TRANSLATIONAL modification
    5 types of modification
    • 1. glycosylation
    • 2. phosphorylation
    • 3. cleavage to active form (proproteins, specific signal needed)
    • 4. folding of polypeptide
    • 5. proteins can form 2-4 structures
    • BOTTOMLINE: don't need to know this BUT know that MANY modifications occur

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