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LEQ: How does RNA help to make a protein?

LEQ: How does RNA help to make a protein?. 10.11 to 10.15. Transfer RNA. Type of RNA that functions as an interpreter in translation Each tRNA molecule has a specific anticodon and a site of attachment for an amino acid Each tRNA picks up a specific amino acid based on its anticodon. tRNA.

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LEQ: How does RNA help to make a protein?

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  1. LEQ: How does RNA help to make a protein? 10.11 to 10.15

  2. Transfer RNA • Type of RNA that functions as an interpreter in translation • Each tRNA molecule has a specific anticodon and a site of attachment for an amino acid • Each tRNA picks up a specific amino acid based on its anticodon

  3. tRNA • Anticodon – specific sequence of 3 exposed nucleotides found in tRNA; complementary to codon of mRNA • 2 important sites • Anticodon • Point of attachment to amino acid

  4. Ribosomal RNA • Type of RNA that, together with proteins, make up ribosomes; most abundant type of RNA • Ribosome composed of 2 subunits – small and large

  5. Eukaryotic vs Prokaryotic Ribosomes • Eukarytoic ribosomes are larger and of different composition • Antibiotics can inactivate prokaryotic ribosomes (but not the eukaryotic ribosomes) can be used to treat bacterial infections

  6. Translation

  7. Initiation • Initiation establishes exactly where translation will begin • 2 steps • mRNA binds to small ribosomal subunit; initiator tRNA binds to the start codon (AUG) of mRNA; tRNA UAC carries Methionine • Large ribosomal subunit binds to the small one placing the initiator tRNA in the P site; A site is open for the next tRNA

  8. Sites of a Ribosome • P site – the ribosomal binding site that holds the tRNA carrying the growing polypeptide (peptidyl tRNA) • A site – the ribosomal binding site that holds the incoming tRNA that holds the new amino acid • E site – the ribosomal release site for tRNA molecules that release the growing polypeptide

  9. Translation

  10. Translation - Elongation • Codon Recognition – incoming tRNA anticodon pairs with mRNA codon in the A site bringing in a new amino acid • Peptide Bond Formation – peptide bond forms between the amino acid in A site and the amino acid in the P site; the tRNA in the P site releases its amino acid once the bond is formed • Translocation – ribosome moves so that the A site tRNA is now in the P site; leaving the A site open for a new tRNA

  11. Translation - Termination • Termination – when the ribosome reaches a stop codon at the A site a release factor binds to the mRNA this triggers the release of the the polypeptide from the last tRNA; mRNA is released from the ribosome and the ribosome subunits separate

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