Chapter33

Chapter33 - BCH 4054 Chapter 33 Lecture Notes Slide 1 The...

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Chapter 33, page 1 BCH 4054 Chapter 33 Lecture Notes Slide 1 Chapter 33 Protein Synthesis The chapter covers degradation of proteins as well. We will not have time to get into that subject. Slide 2 Prokaryotic Ribosomes • 70S particle with 30S and 50S subunits • 30S contains 16S RNA (1542 bases) and 21 peptides • 50S contains 23S RNA (2904 bases), 5S RNA (120 bases) and 31 peptides. • RNA is cut from a precursor operon • (Fig 33.1) • Shapes have been discerned from both EM and X- ray studies. • Fig 33.3 Recall that sizes of macromolecular complexes is operationally defined in terms of the sedimentation rate of the particle in a centrifugation experiment. “S” stands for Svedberg units. It is related to size, but not directly proportional because shape factors also affect sedimentation rate. (See page 157) Slide 3 Eukaryotic Ribosomes • 80S particle with 40S and 60S subunits • 40S contains 18S RNA (1874 bases) and 33 polypeptides • 60S contains 28S RNA (4718 bases), 5.8S RNA (160 bases), 5S RNA (120 bases) and 49 polypeptides • Mitochondria have ribosomes similar to prokaryotic ribosomes
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Chapter 33, page 2 Slide 4 Ribosomal Complex with mRNA and tRNA • The ribosome is the site where mRNA and tRNA are bound in such a way for the anticodon of the tRNA to base pair with the codon of the mRNA • mRNA and protein thread through a “tunnel” formed between the ribosomes. • See Fig 33.4 for a scale model of these interactions. Slide 5 Mechanics of Protein Synthesis • Three phases: initiation, elongation, termination • Each step involves G proteins, and is driven by hydrolysis of GTP • Peptide bond formation catalyzed by RNA component of 50S subunit • Sequence of events is similar in prokaryotes and
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This note was uploaded on 05/22/2011 for the course BCH 4054 taught by Professor Logan/gilmer during the Spring '06 term at FSU.

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Chapter33 - BCH 4054 Chapter 33 Lecture Notes Slide 1 The...

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