RNA and protein synthesis

RNA and protein synthesis - = The (now...

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RNA and protein synthesis, the genetic code The enzymes and rRNAs of the ribosome control the orientation of activated tRNAs to their codons, and the formation of peptide bonds between the amino acids brought in on the tRNAs = At the start of translation, the ribosome assembles near the 5' end of the mRNA, around the start codon (which is almost always 5'-A-U-G-3'), along with the initiator tRNA = The initiator tRNA, which carries a molecule of the amino acid methionine (and the anticodon 5'-C-A-U-3'), base pairs with the start codon in the ribosome's P site = The activated tRNA that matches the next codon then occupies the ribosome's A site = In a reaction catalyzed by the ribosome, the methionine on the initiator tRNA is released from the initiator tRNA and forms a peptide bond with the amino acid on the tRNA in the A site
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Unformatted text preview: = The (now "deactivated") initiator tRNA is released from the ribosome, the second tRNA with its dipeptide is transferred to the P site, and the next activated tRNA comes into the A site, continuing the cycle = Translation is terminated when the A site is over a stop codon (UAA, UAG or UGA); no activated tRNA recognizes these codons- Typically, an mRNA molecule is being simulataneously translated by more than one ribosome, giving rise to the polyribosomes seen in electron micrographs (Tortora Fig 8.7b) Eukaryotic messenger RNA is processed from longer transcripts (Tortora Fig 8.12)- Eukaryotic genes include exons and introns- After RNA polymerase transcribes the DNA, the introns are spliced out of the transcript- The processed mRNA is then transported out of the nucleus...
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