Biochem Chapter 12 p1

Biochem Chapter 12 - Concepts in Biochemistry 3rd Edition Chapter Twelve Translation of RNA The Genetic Code and Protein Metabolism Dr Joe Davis

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Chapter Twelve Translation of RNA: The Genetic Code and Protein Metabolism Concepts in Biochemistry 3rd Edition Dr. Joe Davis Dr. Joe Davis
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Chapter Seven Chapter 12 Homework #1 (Definitions), 2, 5 - 8, 11 - 15, 17, 22 - 24, 25 and 31.
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Chapter Outline 12.1 The Process of Protein Synthesis 12.2 The Three Stages of Protein Synthesis 12.3 Post-translational Processing of Proteins 12.4 Regulation of Protein Synthesis and Gene Expression
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12.1 The Process of Protein Synthesis Characteristics of Translation 1. PROTEIN SYNTHESIS OCCURS ON RIBOSOMES Paul Zamecnik injected radioactive amino acids into mice, removed their livers over time, and determined the locations of the labeled-aa by differential centrifugation. He was 1st to identify organelles called Ribosomes in the cytoplasm as the protein synthesis factories. E. coli ribosomes (shown in Figure 12.1) consist of 2 major subunits of unequal size that dissociate from each other in low Mg 2+ solutions. - Subunit size for the 2 subunits correlated to their centrifugation sedimentation coefficients [S].
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Schematic: Schematic: Fractional Centrifugation Fractional Centrifugation
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12.1 The Process of Protein Synthesis Characteristics of Translation—Ribosomes Prokaryotic Ribosomes Recall: the larger the protein, the higher the S value, and the farther / faster it sediments in the centrifuge tube. E coli have intact ribosomes with S values of 70S; it consists of one smaller 30S subunit and a larger 50S subunit. E.coli ribosomes contain ~66 % RNA and 34% Protein [See Table 12.1a]. Eukaryotic Ribosomes are larger and more complex than Prokaryotic organisms [See Figure 12.1b] They consist of a smaller 40S subunit plus a larger 60S subunit combined to make an 80S Ribosome. There are at least 80 proteins plus 5S, 16S, and 23S rRNA
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Fig 12.1 Fig 12.1 E. coli Ribosome E. coli Ribosome
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Fig 12.1b Fig 12.1b 80S Eukaryotic 80S Eukaryotic Ribosome Ribosome
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12.1 The Process of Protein Synthesis RIBOSOME Function [An Overview] Ribosomes are protein synthesis factories, which perform all steps in protein synthesis: (1) move along the mRNA transcript/template to decipher the code for converting from nucleotide to Amino acid (AA) sequence; (2) bring in tRNA which provides the adaptor molecule charged with the correct AA attached; and (3) catalyze the formation of peptide bonds connecting the AA using energy from ATP and GTP.
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12.1 The Process of Protein Synthesis 2. PROTEIN SYNTHESIS BEGINS AT the AMINO TERMINUS END Early studies [1960s]; using radioactive amino acids showed that the protein synthesis proceeds from the amino terminus end to the carboxyl terminus.
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12.1 The Process of Protein Synthesis 2. PROTEIN SYNTHESIS BEGINS AT AMINO TERMINUS END Studies also helped to determine how quickly protein synthesis occurs: a) a single ribosome synthesized the α- chain of hemoglobin [146 AA; reticulocytes] in ~ 3 minutes.
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12.1 The Process of Protein Synthesis 3. AMINO ACIDS (AA) ARE ACTIVATED and
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Biochem Chapter 12 - Concepts in Biochemistry 3rd Edition Chapter Twelve Translation of RNA The Genetic Code and Protein Metabolism Dr Joe Davis

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