10. translation chapter 27 lehninger 5 th edition
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10. Translation
Chapter 27 Lehninger 5th Edition
Translation
• mRNA gets translated by Ribosomes
Bacterial ribosomes
Eukaryotic ribosomes in ER
The Genetic Code
• 4 bases -> 20 amino acids?
• 42 = 16 43 = 64
• Code = – Triplet code
• 3 bases -> 1 amino acid
– Non-overlapping– Degenerate
The Genetic Code
CodonsCodon usage
Ribosomes
• Need to:– Bind to mRNA
– Recognise start of coding sequence
– Move along coding sequence • Read RNA, codon by codon
• Add amino acids to protein chain
• Need an “adaptor” molecule– tRNA – Transfer RNA
tRNA: Transfer RNA
20 tRNA synthetases
1965: Yeast tRNAala
Ribosomes: 2 subunits• large• small
• S: Svedberg units; centrifugation “size”
Chuck Kurland
SSU rRNA
Translation Initiation
•Bacteria: RBS or Shine Dalgarno sequence•Eukaryotes: ?
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