1 / 9

Translation

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.

euphemia-cathy
Download Presentation

Translation

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Translation Chapter 9

  2. 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

  3. Protein Synthesis • Polymerization of amino acids: condensation reaction (dehydration synthesis)

  4. ~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

  5. ~Universal Genetic Code

  6. NH3+ H-C-CH2SeH COO- Why~Universal? Exceptions • GUG sometimes used as a start • Mammalian mitochondria • Ciliated protozoa • Selenocysteine

  7. 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

  8. 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

  9. 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

More Related