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Topic 7 Cont

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Topic 7 Cont d Transcription and Translation Transcription Basics DNA vs. RNA Transcription Basics cont d Directionality: read 3 -5 ; made 5 -3 ... – PowerPoint PPT presentation

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Title: Topic 7 Cont


1
Topic 7 Contd
  • Transcription and Translation

2
(No Transcript)
3
Transcription Basics
  • DNA vs. RNA

4
Transcription Basics contd
  • Directionality read 3-5 made 5-3
  • Promoter TATA boxes
  • Nucleoside triphosphates
  • Contains the sense strand and antisense strand
  • Sense strand always 5-3 and is the same as
    the mRNA that is produced except T for U
  • Antisense strand always 3-5 and is the strand
    that forms the template and is transcribed.

5
Animation sites
  • http//www.stolaf.edu/people/giannini/flashanimat/
    molgenetics/transcription.swf
  • http//vcell.ndsu.nodak.edu/animations/transcripti
    on/first.htm

6
Translation
  • The process of polypeptide/protein production
    using mRNA as a guide
  • Requires
  • mRNA transcript
  • tRNA
  • tRNA activating enzymes
  • ribosomes
  • genetic code..

7
The Genetic COde
8
The Genetic Code contd
  • Its a triplet code (codon) 3 bases code for 1
    amino acid
  • There are 64 different codons
  • Duplication degeneracy possible for 2 or more
    codons to code for the same amino acid
  • Code is essential universal (find me 2 exceptions
    by next class for 1 point e.c. each)

9
Amino Acids
10
tRNA
  • All tRNAs have base-paired ds sections that
    become loops
  • Triplet bases complementary to mRNA codonscalled
    anticodons
  • A 3-5 CCA terminal end for amino acid
    attachment
  • The above permit 3 distinct binding attachment of
    the tRNA to the ribosome

11
tRNA contd
12
tRNA a S F example
  • The base sequence of tRNa molecules vary some
    variable features in its structure
  • An extra small loop is sometimes present
  • The bp sections are sometimes helical
  • Results in
  • A distinctive 3-d shape
  • Distinctive chemical properties
  • ALLOWS THE CORRECT AA TO BE ATTACHED TO THE 3
    END BY A tRNA ACTIVATING ENZYME (aminoacyl-tRNA
    sythetase)
  • There are 20 different tRNA activating enzymes
    one for each of the 20 diff. AA

13
Ribosome Basics
  • Composed of protein and rRNA
  • Consist of 2 subunits (small and large)
  • Possess 3 binding sites for tRNA (2 tRNAs can
    bind at the same time)
  • Possess a binding site for mRNA
  • Free vs. Bound (RER)
  • 80S in Euks vs. 70S in Proks Euk. organelles

14
Ribosome (2 site version)
15
Translation Step 1 - Initiation
16
(No Transcript)
17
Polysomes Movie Time
  • http//vcell.ndsu.nodak.edu/animations/translation
    /movie.htm
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