Translation
Download
1 / 9

Translation - PowerPoint PPT Presentation


  • 63 Views
  • Uploaded on

Translation. Chapter 9. Overview. Occurs on ribosomes-large aggregates of rRNA and protein tRNA acts as amino acid carriers Prokaryotes—occurs simultaneously with transcription and mRNA degradation Eukaryotes—occurs in cytoplasm mRNA translated 5’ 3’ Protein synthesis aminocarboxy.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Translation' - euphemia-cathy


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Translation

Translation

Chapter 9


Overview
Overview

  • Occurs on ribosomes-large aggregates of rRNA and protein

  • tRNA acts as amino acid carriers

  • Prokaryotes—occurs simultaneously with transcription and mRNA degradation

  • Eukaryotes—occurs in cytoplasm

  • mRNA translated 5’3’

  • Protein synthesis aminocarboxy


Protein synthesis
Protein Synthesis

  • Polymerization of amino acids: condensation reaction (dehydration synthesis)


Universal genetic code
~Universal Genetic Code

  • Codons—sets of 3 nucleotides corresponding to a single amino acid

  • Each codon specifies a single amino acid

  • More than one codon can specify the same amino acid

  • code is said to be degenerate

  • Some aa correspond to a single codon

    • AUG—initiator codon, methionine (Met, M)

    • UGG–Tryoptophan (TrP, W)

  • Often codons encoding the same aa differ onl;y at the 3rd nucleotide



Why universal exceptions

NH3+

H-C-CH2SeH

COO-

Why~Universal? Exceptions

  • GUG sometimes used as a start

  • Mammalian mitochondria

  • Ciliated protozoa

  • Selenocysteine


Selenocysteine
Selenocysteine

  • The 21st amino acid?

  • An essential amino acid for selenoproteins EX. Glutathione oxidase

  • Uses unique tRNA, initially bound to Ser

  • Anticodon recognizes UGA (Stop) as Sec

  • Signals in 3’ region determine Stop or Sec

  • Dedicated specific elongation factor


Degeneracy wobble hypothesis
Degeneracy—Wobble Hypothesis

  • Explains how some tRNA recognize more than one codons

  • tRNA molecules only need to make strong base pairs with 2 of the three codons in the nucleotide

  • This third loose base pairing interaction is called wobble

  • Note: only certain bases can substitute for others


Wobble example
Wobble Example

This UCA codon was read by the

tRNA with a UGA anticodon

But if this UCA was UCG, it would still have been read by the tRNA with a UGA anticodon


ad